#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector< int > vi;
typedef vector< vi > vvi;
typedef vector< ll > vl;
typedef vector< vl > vvl;
typedef pair< int, int > pii;
typedef vector< pii > vp;
typedef vector< double > vd;
typedef vector< vd > vvd;
typedef vector< string > vs;

template< class T1, class T2 >
int upmin( T1 &x, T2 v ){
  if( x > v ){
    x = v;
    return 1;
  }
  return 0;
}

template< class T1, class T2 >
int upmax( T1 &x, T2 v ){
  if( x < v ){
    x = v;
    return 1;
  }
  return 0;
}

const int INF = 0x3f3f3f3f;

int C, D;

void init(){
  cin >> C >> D;
}

void preprocess(){
  double b = ( 3.0 * D - C ) * 7.0 / 13.0;
  double a = ( 1.0 * C - 2.0 / 7.0 * b ) * 4.0 / 3.0;
  double p = min( 4.0 / 3.0 * C, 4.0 * D );
  double q = min( 7.0 / 2.0 * C, 7.0 / 5.0 * D );
  if( a < 0.0 or b < 0.0 )
    a = b = 0.0;
  cout << fixed << setprecision( 9 ) << 
          max( { a * 1000.0 + b * 2000.0, p * 1000.0, q * 2000.0 } ) << endl;
}

void solve(){

}

signed main(){
  ios::sync_with_stdio( 0 );
  init();
  preprocess();
  solve();
  return 0;
}