#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<vector>
#include<map>
#include<queue>
#include<string>
#include<sstream>
#include<cmath>
#include<numeric>
using namespace std;

int main(){

  int a, b;
  cin >> a >> b;
  double tmp = 500 * a / ( 8 + 2 * b ) ;
  int ans = 50 * a + (int)(tmp);
  cout << ans << endl;

  return 0;
}