#include<iostream>
#include<vector>
using namespace std;

int main(){
	int d, g, min = 0;
	cin >> d >> g;
	vector<int> p(d), c(d);
	for (int i=0; i < d; i++) {
		cin >> p[i] >> c[i];
		min += p[i];
	}
	for (int i=0; i<(1<<d) - 1; i++){
		int s = 0;
		int max0 = 0;
		int count = 0;
		for (int j=0; j<d; j++){
			if(i & 1<<j) {
				s += (j+1)* 100 * p[j] + c[j];
				count += p[j];
			} else {
				max0 = j;
			}
		}
		if(s < g && (p[max0] - 1) * (max0+1) * 100 + s >= g) {
			count += (g - s + (max0+1) * 100 - 1) / ((max0+1) * 100);
			s = g;
		}
		if(s >= g && count < min) min = count;
	}
	cout << min << endl;
}

