#include<bits/stdc++.h>
using namespace std;
typedef long long ll;



signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(20);
    
    ll x;
    cin>>x;
    double p;
    cin>>p;
    if(abs(p-100)<0.01){
        x++;
        cout << x/2 << endl;
        return 0;
    }
    p/=100.0;
    if(x%2==0){
        cout << (double)x/2.0/p << "\n";
    }
    else{
        x++;
        cout << (double)x/2.0/p << "\n";
    } 

    
}