#include <bits/stdc++.h>
using namespace std; 
#define rep(i, n) for (int i = 0; i < (n); ++i)
int p[15];
int c[15];

int main() {
	
	
	int d,g;cin>>d>>g;
	
	rep(i,d) cin>>p[i]>>c[i];
	
	int ans = 123456789;
	
	rep(i,(1<<d))
	{
		int score = 0;
		int num = 0;
		rep(j,d)if(i&(1<<j))
		{
			score += (j+1)*100*p[j] + c[j];
			num += p[j];
		}
		
		int ma;
		for(int j=d-1;j>=0;j--)if(!(i&(1<<j))) {ma=j;break;}
		if(score + (p[ma]-1)*100*(ma+1) < g)continue;
		
		int yozyo = score>=g?0:(g-score + 100*(ma+1) - 1) / (100*(ma+1));
	
		ans = min(ans,num+yozyo);
	}
	
	cout << ans << endl;
	
	
	
}