#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
int main() {
	long double a, b;
	cin >> a >> b;
	long double ans = 50 * a + floorl(50 * a / (0.8 + 0.2 * b));
	cout << ans << endl;
}