function Main(s) {
  var s = s.split("\n");
  var d = s[0].split(" ")[0]*1, g = s[0].split(" ")[1]*1;
  var p_c = s.map(e => e.split(" ").map(e => e*1));
  p_c = p_c.slice(1, d+1);
  var min = Infinity;
  for (var bit = 0; bit < (1<<d); bit++) {
    var arr = [];
    var sum = 0;
    var cnt = 0;
    for (var i = 0; i < d; i++) {
      if (bit & (1<<i)) {
        sum += p_c[i][0] * (i + 1)* 100 + p_c[i][1];
        cnt += p_c[i][0];
      } else {
        arr.push(i);
      }
    }
    if (sum < g) {
      var limit = Math.ceil((g - sum) / ((arr[arr.length-1]+1)*100));
      if (limit >= p_c[arr[arr.length-1]][0]) {
        continue;
      } else {
        cnt += limit;
      }
    }
    min = Math.min(min, cnt);
  }
  console.log(min);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));