#include<bits/stdc++.h>
using namespace std;
using Int = long long;
//INSERT ABOVE HERE
Int f(Int n,Int k){
  return 50*n+(500*n/(8+2*k));
}
signed main(){
  Int a,b;
  cin>>a>>b;
  cout<<f(a,b)<<endl;
  return 0;
}