#include<iostream>
#include<vector>
using namespace std;

int main(){
	int D, G; 
	cin >> D >> G;
	vector<int> p(D), c(D);
	for(int i=0;i<D;i++) cin >> p[i] >> c[i];

	int ans = 1e9;
	for(int mask=0;mask<(1<<D);++mask){
		int s=0, num=0, rest_max=-1;
		for(int i=0;i<D;i++){
			if(mask>>i & 1){
				s+=100*(i+1)*p[i]+c[i];
				num+=p[i];
			}else{
				rest_max=i;
			}
		}
		if(s<G){
			int s1=100*(rest_max+1);
			int need=(G-s+s1-1)/s1;
			if(need>=p[rest_max]){
				continue;
			}
			num+=need;
		}
		ans=min(ans,num);
	}
	cout << ans << endl;
}
