#include <bits/stdc++.h>
using namespace std;
using ll=long long;
const long double eps = 1e-10;

int main() {
    long double x;
    cin >> x;
    long double ans = 0;
    for(int i=0;i<int(1e5)+5;i++){
        if(i +x  <= eps){
            ans += 1.0;
            continue;
        }
        ans += powl(sinl(x+i)/(x+i),2.0);
    }
    cout << setprecision(20) <<ans << endl;

    return 0;
}