#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if(x < y) x = y; }

int main() {
	int C; int D;
	while(~scanf("%d%d", &C, &D)) {
		double a = 3. / 4, b = 2. / 7, c = 1. / 4, d = 5. / 7, e = C, f = D;
		double price[2] = { 1e3, 2e3 };
		double ans = 0;
		amax(ans, min(C / a, D / c) * price[0]);
		amax(ans, min(C / b, D / d) * price[1]);
		double det = a * d - b * c;
		double x = (d * e - b * f) / det;
		double y = (a * f - c * e) / det;
		if(0 <= x && 0 <= y)
			amax(ans, x * price[0] + y * price[1]);
		printf("%.10f\n", ans);
	}
	return 0;
}