Problem:
Score : 300 points

Problem Statement

A programming competition site AtCode provides algorithmic problems.
Each problem is allocated a score based on its difficulty.
Currently, for each integer i between 1 and D (inclusive), there are p_i problems with a score of 100i points.
These p_1 + … + p_D problems are all of the problems available on AtCode.

A user of AtCode has a value called total score.
The total score of a user is the sum of the following two elements:

Base score: the sum of the scores of all problems solved by the user.

Perfect bonuses: when a user solves all problems with a score of 100i points, he/she earns the perfect bonus of c_i points, aside from the base score (1 ≤ i ≤ D).

Takahashi, who is the new user of AtCode, has not solved any problem.
His objective is to have a total score of G or more points.
At least how many problems does he need to solve for this objective?

Constraints

1 ≤ D ≤ 10

1 ≤ p_i ≤ 100

100 ≤ c_i ≤ 10^6

100 ≤ G

All values in input are integers.

c_i and G are all multiples of 100.

It is possible to have a total score of G or more points.

Input

Input is given from Standard Input in the following format:

D G
p_1 c_1
:
p_D c_D

Output

Print the minimum number of problems that needs to be solved in order to have a total score of G or more points. Note that this objective is always achievable (see Constraints).

Sample Input 1

2 700
3 500
5 800

Sample Output 1

3

In this case, there are three problems each with 100 points and five problems each with 200 points. The perfect bonus for solving all the 100-point problems is 500 points, and the perfect bonus for solving all the 200-point problems is 800 points. Takahashi's objective is to have a total score of 700 points or more.

One way to achieve this objective is to solve four 200-point problems and earn a base score of 800 points. However, if we solve three 100-point problems, we can earn the perfect bonus of 500 points in addition to the base score of 300 points, for a total score of 800 points, and we can achieve the objective with fewer problems.

Sample Input 2

2 2000
3 500
5 800

Sample Output 2

7

This case is similar to Sample Input 1, but the Takahashi's objective this time is 2000 points or more. In this case, we inevitably need to solve all five 200-point problems, and by solving two 100-point problems additionally we have the total score of 2000 points.

Sample Input 3

2 400
3 500
5 800

Sample Output 3

2

This case is again similar to Sample Input 1, but the Takahashi's objective this time is 400 points or more. In this case, we only need to solve two 200-point problems to achieve the objective.

Sample Input 4

5 25000
20 1000
40 1000
50 1000
30 1000
1 1000

Sample Output 4

66

There is only one 500-point problem, but the perfect bonus can be earned even in such a case.

Solution in JavaScript (node.js v5.12) (judge verdict: Accepted)

function main(input) {
  var D = input[0].split(" ")[0]-0;
  var G = input[0].split(" ")[1]-0;
  var lines = [];
  var pafemap = [];
  for(var i=1;i<=D;i++){
    lines.push(input[i].split(" ").map(v=>v-0));
    pafemap.push(i*100*lines[i-1][0]+lines[i-1][1]);
  }
  var ans = 100*100;
  for(var i=0;i<Math.pow(2,D);i++){
    var st = ("0000000000" + i.toString(2)).slice(-D);
    var score = 0;
    var nums = 0;
    var npafe = [];
    for(var j=0;j<st.length;j++){
      if(st[j]=="1"){
        score += pafemap[j];
        nums += lines[j][0];
      }else{
        npafe.push({
          i: j+1, num: lines[j][0],
        });
      }
    }
    if(score<G){
      npafe.reverse();
      for(var j=0;j<npafe.length;j++){
        var num = npafe[j].num-1;
        var scr = npafe[j].i*100;
        if(score+scr*num<G){
          score+=scr*num;
          nums+=num;
        }else{
          var n = Math.min(num, Math.ceil((G-score)/scr));
          score+=scr*n;
          nums+=n;
          break;
        }
      }
    }
    if(score>=G)
      ans = Math.min(ans, nums);
  }
  console.log(ans);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8').trim().split("\n"))