#include<cstdio>

int d, g, p, c, dp[1003];

int max(int x, int y) {
	return x > y ? x : y;
}

int main() {
	scanf("%d %d", &d, &g);
	for (int i = 1; i <= d; i++) {
		scanf("%d %d", &p, &c);
		for (int j = 1000; j >= 0; j--) {
			if (j != 0 && dp[j] == 0) {
				continue;
			}
			for (int k = 0; k < p; k++) {
				dp[j + k] = max(dp[j + k], dp[j] + 100 * k * i);
			}
			dp[j + p] = max(dp[j + p], dp[j] + 100 * p * i + c);
		}
	}
	for (int i = 1; i <= 1000; i++) {
		if (dp[i] >= g) {
			printf("%d\n", i);
			break;
		}
	}
}