#include <iostream>
#include <cstdio>

using namespace std;

int c, d;
double ans;

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

    scanf("%d%d", &c, &d);

    // 只A
    ans = max(ans, 1000 * min(1.0 * c / (3.0 / 4), 1.0 * d / (1.0 / 4)));
    // 只B
    ans = max(ans, 2000 * min(1.0 * c / (2.0 / 7), 1.0 * d / (5.0 / 7)));
    // AB都有
    double x = (0.0 + 20 * c - 8 * d) / 13;
    double y = (0.0 + 21 * d - 7 * c) / 13;
    if (x >= 0.0 && y >= 0.0) {
        ans = max(ans, 1000 * x + 2000 * y);
    }

    printf("%.10lf\n", ans);

    return 0;
}