#include <bits/stdc++.h>
using namespace std;
int dp[1005];
int main(){
	memset(dp, -1, sizeof(dp));
	int d, g;
	scanf("%d%d", &d, &g);
	dp[0] = 0;
	int mx = 0;
	for(int i=1;i<=d;i++){
		int p, c;
		scanf("%d%d", &p, &c);
		for(int j=mx;j>=0;j--){
			if(dp[j] == -1) continue;
			for(int k=1;k<=p;k++){
				if(k != p) dp[j+k] = max(dp[j+k], dp[j] + 100*i*k);
				else dp[j+k] = max(dp[j+k], dp[j] + 100*i*k + c);
			}
			mx = max(mx, j+p);
		}
	}
	for(int i=0;i<=1000;i++){
		if(dp[i] >= g) return !printf("%d\n", i);
	}
}