#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>
#include <numeric>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
constexpr long long MAX = 5100000;
constexpr long long INF = 1LL << 60;
constexpr int inf = 1000000007;
constexpr long long mod = 1000000007LL;
//constexpr long long mod = 998244353LL;
const long double PI = acos((long double)(-1));

using namespace std;
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;

using Real = double;
Real C, D;
Real f(Real c1) {
    Real d1 = min(D, c1 / 3.0);
    Real d2 = D - d1;
    chmin(c1, d1 * 3);
    Real c2 = C - c1;
    chmin(c2, d2 * 2.0 / 5.0);
    return d1 * 4 * 1000 + c2 * 7 / 2.0 * 2000;
}

int main()
{
    /*
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    */


    {int _C, _D; scanf("%d %d", &_C, &_D), C = _C, D = _D; }
    Real lf = 0;
    Real rg = C;
    for (int kkt = 0; kkt <= 89; kkt++) {
        Real lmid = (lf * 2 + rg) / 3.0;
        Real rmid = (lf + rg * 2) / 3.0;
        if (f(lmid) > f(rmid)) rg = rmid;
        else lf = lmid;
    }
    cout << fixed << setprecision(12) << f(lf) << endl;
    return 0;
}