#include <algorithm>
#include <cassert>
#include <cctype>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstring>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <vector>
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define show(x) cout << #x << " = " << x << endl;
using namespace std;
using ll = long long;
using pii = pair<int,int>;
int main(){
    int x;
    double p;
    cin >> x >> p;
    p/=100.0;
    if(1){
        cout << fixed << setprecision(10) << (x+1)/2/p << endl;
    }
}