#include <bits/stdc++.h>
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.at(i) >> c.at(i);
	}

	int ans = 1 << 29;
	for(int i=0; i < (1 << d); i++) {
		int sum = 0, count = 0, last = -1;
		for(int j=0; j < d; j++) {
			if(i & (1 << j)) {
				sum += 100 * (j+1) * p.at(j) + c.at(j);
				count += p.at(j);
			}else{
				last = j;
			}
		}
		if(sum < g) {
			int point = 100 * (last + 1);
			int need =  (g - sum + (point-1)) / point;
			if(need >= p[last]) continue;
			count += need;
		}
		ans = min(ans, count);
	}
	cout << ans << endl;
}
