#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vint;
typedef pair<int,int> pint;
typedef vector<pint> vpint;
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
#define each(it,v) for(__typeof((v).begin()) it=(v).begin();it!=(v).end();it++)
#define all(v) (v).begin(),(v).end()
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define chmax(a, b) a = (((a)<(b)) ? (b) : (a))
#define chmin(a, b) a = (((a)>(b)) ? (b) : (a))
const int MOD = 1e9 + 7;
const int INF = 1e9;

double c, d;
double ans;
double search(double a){
    double tc = c, td = d;
    double ret = 0.0;
    if(tc >= a * 3.0 / 4.0 && td >= a * 1.0 / 4.0){
        tc -= a * 3.0 / 4.0;
        td -= a * 1.0 / 4.0;
        ret += a * 1000.0;
    }else{
        return 0;
    }

    //残りはすべてBを作る。
    ret += 2000.0 * (min(tc * 7.0 / 2.0, td * 7.0 / 5.0));
    ans = ret;
    return ret;
}

int main(void){
    cin >> c >> d;
    //下凸関数を三分探索

    double l = 0.0;
    double r = 2000.0;
    rep(i, 10000){
        //m は、製品Aを作る量
        double m1 = (l * 2.0 + r) / 3.0;
        double m2 = (l + r * 2.0) / 3.0;
        if(search(m1) < search(m2)){//右が高い
            l = m1;
        }else{//左側が高い
            r = m2;
        }
    }
    printf("%.9f\n", ans);
    return 0;
}