#include<iostream>

using namespace std;
const double hoge=1e-6;

int f(int N, int K){

   return 50*N+(int)(hoge+(50*N)/(0.8+0.2*K));
}

int main(){

   int A, B;
   cin>> A>> B;

   cout<< f(A, B)<< endl;

   return 0;
}