#include<bits/stdc++.h>
#define mx 100005
using namespace std;

int main(){
	int d, g, p[12], c[12], fans = 1005;
	scanf("%d%d", &d, &g);
	g /= 100;
	for(int i = 0; i < d; i++){
		scanf("%d%d", &p[i], &c[i]);
		c[i] /= 100;
	}
	for(int i = 0; i < (1<<d); i++){
		int point = 0, ans = 0;
		for(int j = 0; j < d; j++){
			if((i>>j)&1){
				point += p[j]*(j+1) + c[j];
				ans += p[j];
			}
		}
		if(point < g){
			int j = d-1;
			for(; (i>>j)&1 && j >= 0; j--);
			if(j < 0) continue;
			int k = min(p[j], (g - point - 1)/(j+1)+1);
			point += k*(j+1);
			ans += k;
		}
		if(point >= g && ans < fans) fans = ans;
	}
	printf("%d\n", fans);
}
