#include <bits/stdc++.h>
#define int long long
#define r(i,n) for(int i=0;i<n;i++)
using namespace std;
typedef pair<int,int>P;
typedef pair<int,P>P2;

signed main(){
  int n,m,ans=1e9;
  cin>>n>>m;
  int p[n],c[n];
  r(i,n)cin>>p[i]>>c[i];
  for(int i=0;i<(1<<n);i++){
    int s=0,sco=0;
    r(j,n)if(i&(1<<j))s+=p[j],sco+=c[j]+(100*(j+1))*p[j];
    if(sco>=m){
      ans=min(ans,s);
      continue;
    }
    vector<int>v;
    r(j,n)if(!(i&(1<<j))){
      r(k,p[j])v.push_back(100*(j+1));
    }
    sort(v.begin(),v.end(),greater<int>());
    r(j,v.size()){
      s++;
      sco+=v[j];
      if(sco>=m)break;
    }
    ans=min(ans,s);
  }
  cout<<ans<<endl;
}