#include <iostream>
#include<algorithm>
using namespace std;
int main() {
	int D, G, p[11], c[11];
	cin >> D >> G;
	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;
}
