#include <iostream>
#include <cmath>
#include <unordered_set>
using namespace std;

int main() {
    long long n;
    cin >> n;

    unordered_set<long long> balanced;
    for (long long a = 1; a * a <= n; ++a) {
        long long sq = a * a;
        long long prod = a * (a + 1);
        if (sq <= n) balanced.insert(sq);
        if (prod <= n) balanced.insert(prod);
    }

    cout << balanced.size() << endl;
    return 0;
}