#include <bits/stdc++.h>
using namespace std;
int main()
{
    double x;
    cin >> x;
    double mid, temp, check = 0;
    double low = 0, high = x;
    mid = (low + high) / 2;
    while((mid * mid) != x){
        if(check != 0) mid = (low + high) / 2;
        check = 1;
        temp = mid * mid;

        if(temp > x){
            high = mid;

        }
        else if(temp < x){
            low = mid;
        }
    }
    cout << mid << endl;

    return 0;
}