#include <cstdio>
#include <cstring>
#include <string>
#include <iostream>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <unordered_map>
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

int main()
{
	ll x; double p;
  cin>>x>>p;
  if(x%2) printf("%.7lf\n", ((double)x+1)/2/p*100);
  else printf("%.7lf\n", ((double)x)/2/p*100);
	return 0;
}