#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

void solve();
signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
    return 0;
}

/*================================*/

double C,D;

double calB(double c, double d) {
    return min(c * 7 / 2 , d * 7 / 5) * 2000;
}

double price(double a) {
    double c = C - a * 3/4;
    double d = D - a * 1/4;
    return a * 1000 + calB(c, d);
}

void solve() {
    cin>>C>>D;
    
    double amin = 0;
    double amax = min(C * 4 / 3, D * 4);
    double ans = 0;
    REP(i,1e5) {
        // a1>a0;
        double a0 = amin + (amax - amin) * 1 / 3;
        double a1 = amin + (amax - amin) * 2 / 3;
        double pa = price(a0);
        double pb = price(a1);
        if (pa > pb) {
            amax = a1;
        } else {
            amin = a0;
        }
        ans = max(ans, max(pa, pb));
    }
    
    out("%.14lf\n", ans);
}