function Main(input) {
  input = input.split("\n");
  var d = parseInt(input[0].split(" ")[0]);
  var g = parseInt(input[0].split(" ")[1]);
  p = new Array(d).fill(0);
  c = new Array(d).fill(0);

  for(i=0;i<d;i++){
    p[i]=parseInt(input[i+1].split(" ")[0]);
    c[i]=parseInt(input[i+1].split(" ")[1]);
  }
  a = new Array(d).fill(0);
  for(i=0;i<d;i++){
    a[i]=((i+1)*100)*p[i]+c[i];
  }
  var min = 10000000;
  m = new Array(d).fill(0);
  for(i1=0;i1<2;i1++){
    var x=0;
    var n=0;
    x += a[0]*(i1);
    n += p[0]*(i1);
    m[d-1] = 1*(i1);
    if(d<2){
      if(x<=g){
        n += Math.ceil((g-x)/((d-m.indexOf(0))*100));
      }
      min = Math.min(min,n);
    }else{
      for(i2=0;i2<2;i2++){
        var o2 = x;
        x += a[1]*(i2);
        var o = n;
        n += p[1]*(i2);
        m[d-2] = 2*(i2);
        if(d<3){
          if(x<=g&&Math.ceil((g-x)/((d-m.indexOf(0))*100))<=p[d-m.indexOf(0)-1]){
            n += Math.ceil((g-x)/((d-m.indexOf(0))*100));
          }else if(x>=g){
            n= n;
          }else{
            n = 10000000;
          }
          min = Math.min(min,n);
          n=o;
          x=o2;
        }else{
          for(i3=0;i3<2;i3++){
            var o2 = x;
            x += a[2]*(i3);
            var o = n;
            n += p[2]*(i3);
            m[d-3] = 3*(i3);
            if(d<4){
              if(x<=g&&Math.ceil((g-x)/((d-m.indexOf(0))*100))<=p[d-m.indexOf(0)-1]){
                n += Math.ceil((g-x)/((d-m.indexOf(0))*100));
              }else if(x>=g){
                n= n;
              }else{
                n = 10000000;
              }
              min = Math.min(min,n);
              n=o;
              x=o2;
            }else{
              for(i4=0;i4<2;i4++){
                var o2 = x;
                x += a[3]*(i4);
                var o = n;
                n += p[3]*(i4);
                m[d-4] = 4*(i4);
                if(d<5){
                  if(x<=g&&Math.ceil((g-x)/((d-m.indexOf(0))*100))<=p[d-m.indexOf(0)-1]){
                    n += Math.ceil((g-x)/((d-m.indexOf(0))*100));
                  }else if(x>=g){
                    n= n;
                  }else{
                    n = 10000000;
                  }
                  min = Math.min(min,n);
                  n=o;
                  x=o2;
                }else{
                  for(i5=0;i5<2;i5++){
                    var o2 = x;
                    x += a[4]*(i5);
                    var o = n;
                    n += p[4]*(i5);
                    m[d-5] = 5*(i5);
                    if(d<6){
                      if(x<=g&&Math.ceil((g-x)/((d-m.indexOf(0))*100))<=p[d-m.indexOf(0)-1]){
                        n += Math.ceil((g-x)/((d-m.indexOf(0))*100));
                      }else if(x>=g){
                        n= n;
                      }else{
                        n = 10000000;
                      }
                      min = Math.min(min,n);
                      n=o;
                      x=o2;
                    }else{
                      for(i6=0;i6<2;i6++){
                        var o2 = x;
                        x += a[5]*(i6);
                        var o = n;
                        n += p[5]*(i6);
                        m[d-6] = 6*(i6);
                        if(d<7){
                          if(x<=g&&Math.ceil((g-x)/((d-m.indexOf(0))*100))<=p[d-m.indexOf(0)-1]){
                            n += Math.ceil((g-x)/((d-m.indexOf(0))*100));
                          }else if(x>=g){
                            n= n;
                          }else{
                            n = 10000000;
                          }
                          min = Math.min(min,n);
                          n=o;
                          x=o2;
                        }else{
                          for(i7=0;i7<2;i7++){
                            var o2 = x;
                            x += a[6]*(i7);
                            var o = n;
                            n += p[6]*(i7);
                            m[d-7] = 7*(i7);
                            if(d<8){
                              if(x<=g&&Math.ceil((g-x)/((d-m.indexOf(0))*100))<=p[d-m.indexOf(0)-1]){
                                n += Math.ceil((g-x)/((d-m.indexOf(0))*100));
                              }else if(x>=g){
                                n= n;
                              }else{
                                n = 10000000;
                              }
                              min = Math.min(min,n);
                              n=o;
                              x=o2;
                            }else{
                              for(i8=0;i8<2;i8++){
                                var o2 = x;
                                x += a[7]*(i8);
                                var o = n;
                                n += p[7]*(i8);
                                m[d-8] = 8*(i8);
                                if(d<9){
                                  if(x<=g&&Math.ceil((g-x)/((d-m.indexOf(0))*100))<=p[d-m.indexOf(0)-1]){
                                    n += Math.ceil((g-x)/((d-m.indexOf(0))*100));
                                  }else if(x>=g){
                                    n= n;
                                  }else{
                                    n = 10000000;
                                  }
                                  min = Math.min(min,n);
                                  n=o;
                                  x=o2;
                                }else{
                                  for(i9=0;i9<2;i9++){
                                    var o2 = x;
                                    x += a[8]*(i9);
                                    var o = n;
                                    n += p[8]*(i9);
                                    m[d-9] = 9*(i9);
                                    if(d<10){
                                      if(x<=g&&Math.ceil((g-x)/((d-m.indexOf(0))*100))<=p[d-m.indexOf(0)-1]){
                                        n += Math.ceil((g-x)/((d-m.indexOf(0))*100));
                                      }else if(x>=g){
                                        n= n;
                                      }else{
                                        n = 10000000;
                                      }
                                      min = Math.min(min,n);
                                      n=o;
                                      x=o2;
                                    }else{
                                      for(i10=0;i10<2;i10++){
                                        var o2 = x;
                                        x += a[9]*(i10);
                                        var o = n;
                                        n += p[9]*(i10);
                                        m[d-10] = 10*(i10);
                                        if(d<11){
                                          if(x<=g&&Math.ceil((g-x)/((d-m.indexOf(0))*100))<=p[d-m.indexOf(0)-1]){
                                            n += Math.ceil((g-x)/((d-m.indexOf(0))*100));
                                          }else if(x>=g){
                                            n= n;
                                          }else{
                                            n = 10000000;
                                          }
                                          min = Math.min(min,n);
                                          n=o;
                                          x=o2;
                                        }
                                      }
                                    }
                                  }
                                }
                              }
                            }
                          }
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
  console.log('%s', min);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));