#include<bits/stdc++.h>
#define INF 0x3f3f3f3f
#define rep(i,n)for(int i=0;i<n;i++)
using namespace std;
typedef long long ll;
typedef pair<int, int>P;

double f(double n, double k) {
	return 50. * n + floor((50. * n) / (0.8 + 0.2*k));
}
int main() {
	double a, b; cin >> a >> b;
	cout << (ll)f(a, b) << endl;
}