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#include <bits/stdc++.h>
using namespace std;
double mySqrt(int n) {
    if (n == 0) return 0;
    double left = 0;
    double right = n;
    double mid;
    while (right - left > 0.0001) {  // 控制精度
        mid = (left + right) / 2.0;
        if (mid * mid < n)
            left = mid;
        else
            right = mid;
    }
    return left;
}
int main() {
    int n;
    cin >> n;
    double ans = mySqrt(n);
    cout << fixed << setprecision(2) << ans << endl;
    return 0;
}