#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>
using namespace std;
int N, K;
int main(){
    cin >> N >> K;
    double d = floor((50 * N) / (0.8 + 0.2 * K));
    cout << 50*N + d << endl;
    return 0;
}