#include<iostream>
#include<vector>
#include<string>
#include<cstring>
#include<algorithm>
#include<map>
#include<set>
#include<cmath>
#include<cassert>
#include<queue>

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef vector<int> vi;

int C, D;
double calc(double a) {
	double b = min((C-3*a/4)*7/2, (D-a/4)*7/5);
	if (b < 0) b = 0;
	return 1000*a + 2000*b;
}

int main() {
	cin >> C >> D;
	double low = 0, high = min(4.*C/3, 4.*D);
	for (int t = 0; t < 100; ++t) {
		const double m1 = (2*low+high)/3;
		const double m2 = (low+2*high)/3;
		if (calc(m1) < calc(m2)) low = m1;
		else high = m2;
	}
	printf("%.10lf\n", calc((low+high)/2));
	return 0;
}