#include <bits/stdc++.h>
using namespace std;

int soredake(int point, int kazu, int bonasu, int goal) {
  int tokukazu = goal / point;
  if (goal % point > 0) {
    tokukazu++;
  }
  if (tokukazu > kazu) {
    tokukazu = kazu;
  }
  return tokukazu;
}

int search(vector<vector<int>> questions, int goal) {

  int minimum = 0;
  for (int i = 0; i < questions.size(); i++) {
    minimum += questions.at(i).at(1);
  }
  for (int i = 0; i < questions.size(); i++) {
    int point = questions.at(i).at(0);
    int kazu = questions.at(i).at(1);
    int bonasu = questions.at(i).at(2);
    int goukei = questions.at(i).at(3);

    vector<vector<int>> q = questions;
    q.erase(q.begin() + i);
    if (goukei < goal) {
      int nokori = search(q, goal - goukei) + kazu;
      if (nokori < minimum) {
        minimum = nokori;
      }
    } else {
      int nokori = soredake(point, kazu, bonasu, goal);
      if (nokori < minimum) {
        minimum = nokori;
      }
    }
  }
  return minimum;
}

int main() {
  int d, g;
  cin >> d >> g;

  vector<vector<int>> questions(d, vector<int>(4));
  for (int i = 0; i < d; i++) {
    questions.at(i).at(0) = 100 * (i + 1);
    cin >> questions.at(i).at(1);
    cin >> questions.at(i).at(2);
    questions.at(i).at(3) =
        questions.at(i).at(0) * questions.at(i).at(1) + questions.at(i).at(2);
  }

  cout << search(questions, g) << endl;
}

#include <bits/stdc++.h>
#include <string>
#include <vector>
#include <algorithm>
#define rep(i,w) for (int i = 0;i < (w); ++i)
using namespace std;
using ll = long long;
using P = pair<int,int>;
int INF = 1e9;

int main(){
  int d,g;cin >> d >> g;
  vector<int> p(10),c(10);
  rep(i,d) cin >> p[i] >> c[i];
  int ind = 0;
  int sum = 0;
  int ans = INF;
  int cnt = 0;
  rep(i,1<<d){
    sum = 0;
    cnt = 0;
    rep(j,d){
      if(i>>j&1) {
        sum += p[j]*(j+1)*100;
        sum += c[j];
        cnt += p[j];
      }else ind = j;
    }
    if(g-sum > (p[ind]-1)*(ind+1)*100) continue;
    cnt += max(g-sum + (ind+1)*100 -1,0)/((ind+1)*100);
    ans = min(ans,cnt);
  }

  cout << ans << endl;
}