#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cmath>
#include<cctype>
#include<math.h>
#include<string>
#include<string.h>
#include<stack>
#include<queue>
#include<vector>
#include<utility>
#include<set>
#include<map>
#include<stdlib.h>
#include<iomanip>

using namespace std;

#define ll long long
#define ld long double
#define EPS 0.0000000001
#define INF 1e9
#define LINF (ll)INF*INF
#define MOD 1000000007
#define rep(i,n) for(int i=0;i<(n);i++)
#define loop(i,a,n) for(int i=a;i<(n);i++)
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)

#define int ll //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

typedef vector<int> vi;
typedef vector<string> vs;
typedef pair<int,int> pii;
typedef vector<pii> vp;

int gcd(int a, int b){
    if(b==0) return a;
    return gcd(b,a%b);
}
int lcm(int a, int b){
    return a/gcd(a,b)*b;
}

int c,d;
double ans;

double f(double a){// 製品 A を a kg　つくる
    ans = a * 1000 + min((c - a * 0.75) * 7 / 2, (d - a * 0.25) * 7 / 5) * 2000;
    return ans;
}

signed main(void) {
    cin >> c >> d;
    double lb = 0, ub = min(c/0.75, d/0.25);
    rep(_,200){
        double m1 = (lb + lb + ub) / 3;
        double m2 = (lb + ub + ub) / 3;
        if(f(m1) > f(m2))ub = m2;
        else lb = m1;
    }
    cout << shosu(10) << ans << endl;
}