// clang-format off
#include <bits/stdc++.h>

#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 rep1(i,n) for(int i = 1; i <= (n); i++)
#define rrep(i, n) for(int i = (n)-1; i >= 0; i--)

#define pb push_back
#define mp make_pair
#define fst first
#define snd second
#define show(x) cout << #x << " = " << x << endl
#define chmin(x,y) x=min(x,y)
#define chmax(x,y) x=max(x,y)
#define pii pair<int, int>
#define vi vector<int>

using namespace std;
template<class S,class T> ostream& operator<<(ostream& o,const pair<S,T>& p){return o<<"("<<p.first<<","<<p.second<<")";}
template<class T> ostream& operator<<(ostream& o,const vector<T>& vc){o<<"sz = "<<vc.size()<<endl<<"[";for(const T& v:vc) o<<v<<",";o<<"]";return o;}
using ll = long long;
constexpr ll MOD = 1000000007;



int main()
{
    int C, D;
    cin >> C >> D;
    if(2*D >= 5*C){
        cout << 7000*C << endl;
    } else if(C >= 3*D){
        cout << 4000*D << endl;
    } else {
        cout << fixed << setprecision(10) << (long double)(6*C+34*D)*1000/13 << endl;
    }

    return 0;
}