#include <bits/stdc++.h>
using namespace std;
int main(){
	long long X, P; 
	cin >> X >> P; 
	double ans; 
	if(X % 2 == 0) ans = 50.0 * X / P; 
	else ans = 50.0 * (X + 1.0) / P; 
	cout.precision(15); 
	cout << ans << endl; 
}