#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

int a, b;

int main() {
  cin >> a >> b;
  //cout << fixed << setprecision(15) << (50.0 * a) / (0.8 + 0.2 * b) << endl;
  cout << 50 * a + floor((50.0 * a) / (0.8 + 0.2 * b) + 1e-10) << endl;
  return 0;
}