#include <algorithm>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rrep(i, n) for (int i = (n)-1; i >= 0; i--)
using namespace std;
typedef long long int lli;
lli MOD = 1000000007;
int main()
{
    auto f = [](int n, int k) -> int {
        return 50 * n + (250 * n / (4 + k));
    };
    int a, b;
    cin >> a >> b;
    cout << f(a, b) << endl;
}