#include <bits/stdc++.h>
#define FOR(i,bg,ed) for(ll i=(bg);i<(ed);i++)
#define REP(i,n) FOR(i,0,n)
#define MOD 1000000007
#define int long long
using namespace std;
typedef long long ll;
const int INF = 1e9;

int f(int N, int K)
{
    int ret = (50 * N) / (0.8 + 0.2 * K) + 0.01;
    return 50 * N + ret;
}

signed main()
{
    int A, B;

    cin >> A >> B;
    cout << f(A, B) << endl;
}