#define _CRT_SECURE_NO_WARNINGS
#include<sstream>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<climits>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
#include<tuple>
#include<unordered_set>
#include<random>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())






int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	double ans = 0;
	double c, d, e, f;
	cin >> c >> d;

	double x = max(0.0, (3 * d - c) * 7 / 13);
	e = c - x * (2.0 / 7);
	f = d - x * (5.0 / 7);
	if (0 <= e && 0 <= f)ans = x * 2000 + min(e / (3.0 / 4), f / (1.0 / 4)) * 1000;


	x = max(0.0, (20 * c - 8 * d) / 13);
	e = c - x * (3.0 / 4);
	f = d - x * (1.0 / 4);
	if (0 <= e && 0 <= f)ans = max(ans, x * 1000 + min(e / (2.0 / 7), f / (5.0 / 7)) * 2000);

	
	printf("%.6f\n", ans);



	return 0;
}