#define _GLIBCXX_DEBUG
#define ll long long
#include <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;

int main(){
  ll A, B; cin >> A >> B;
  ll X = 50*A;
  ll Y = 250*A;
  ll Z = 4+B;
  ll YZ = Y/Z;
  cout << X + YZ << endl;
}