#include <iostream>
#include <cstdio>

using namespace std;

int a, b;

int main() {
    // freopen("score.in", "r", stdin);
    // freopen("score.out", "w", stdout);

    scanf("%d%d", &a, &b);

    printf("%d\n", 50 * a + 250 * a / (b + 4));

    return 0;
}