#include <bits/stdc++.h>
#define PI 3.14159265359
using namespace std;

int main() {
	int A, B;
	cin >> A >> B;

	int n = 500 * A;
	double m = 2 * B + 8;
	int ans = (int)n / m;
	ans += 50 * A;
	
	cout << ans << endl;
}