#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i,a) for(int i=0;i<(a);i++)
const ll MOD=1000000007;

int dp[22][2020];

int main(){
  int D,G; cin>>D>>G;
  int P[D],C[D];
  int cnt=0;
  rep(i,D){
    cin>>P[i]>>C[i];
    cnt+=P[i];
  }
  rep(i,22) rep(j,2020) dp[i][j]=-1;
  dp[0][0]=0;
  int ans=1e9;
  rep(i,D) rep(j,cnt+1) if(dp[i][j]!=-1){
    for(int k=0;k<=P[i];k++){
      int tmp=0;
      if(k==P[i]) tmp=C[i];
      dp[i+1][j+k]=max(dp[i+1][j+k],dp[i][j]+(100*(i+1)*k)+tmp);
      if(dp[i+1][j+k]>=G) ans=min(ans,j+k);
    }
  }
  cout<<ans<<endl;
  return 0;
}
