#include <iostream>
#include <algorithm>
#include <cstring>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <cmath>
#include <map>

#define AS(a) (sizeof(a)/sizeof(a[0]))
using namespace std;
long long int MOD = 1000000007;
long long int INF = 1000000007;


int main() {
  int a,b;
  cin >> a >> b;
  cout << 50 * a + floor((250 * a) / (4 + b)) << endl;
}