function Main(s){
  s = s.split("\n");
  var d = s[0].split(" ").map(a=>+a);
  var g = d[1] / 100;
  d = d[0];
  var p = [];
  for(var i = 0; i < d; i++){
    p[i] = s[i+1].split(" ").map(a=>+a);
    p[i][1] /= 100;
    p[i][1] = p[i][0] * (i+1) + p[i][1];
  }
  var ans = 9e9;
  for(i = 0; i < 1<<d; i++){
    var u = 0, v = 0, w = -1;
    for(var j = 0; j < d; j++){
      if(i & (1<<j)){u += p[j][0]; v += p[j][1]}
      else w = j;
    }
    var t = 0;
    if(w >= 0)while(v < g && t++ < p[w][0]){
      u++;
      v += w + 1;
    }
    if(v >= g && ans > u)ans = u;
  }
  console.log(ans);
}

Main(require("fs").readFileSync("/dev/stdin","utf8"));