Q.17

#include <iostream>
using namespace std;

long long solve(long long a) {
    long long l = 0, r = 1e9 + 1;
    while (l < r - 1) {
        long long m = (l + r) / 2;
        if (m * m <= a)
            l = m;
        else
            r = m;
    }
    return l;
}

int main()
{
    long long a;
    cin >> a;
    cout << solve(a);
    return 0;
}