#include <iostream>
#include <cmath>
using namespace std;
int main() {
    long long c;
    cin >>c;
    long long l = 0, r = c, m = (l + r) /2;
    while (abs(c - (pow(m, 2) + pow(m, 0.5))) < 0.000001){
        m = (l + r) / 2;
        cout << "yeye";
        if (pow(m, 2) + pow(m, 0.5) < c){
            l = m;
        }
        else {
            if (pow(m, 2) + pow(m, 0.5) > c) {
                r = m;
            }
        }

    }
    cout << m;
}