/**
* Author: Sergey Kopeliovich (Burunduk30@gmail.com)
* Two times faster under 64-bit compiler
*/
#include <ctime>
#include <cstdio>
#include <cassert>
#include <iostream>
using namespace std;
#define forn(i, n) for (int i = 0; i < (int)(n); i++)
int main() {
#define NAME "testtime"
assert(freopen(NAME ".in", "r", stdin));
assert(freopen(NAME ".out", "w", stdout));
long long n, sum = 0, k;
cin >> n;
for (k = 1; k * k <= n; k++)
sum += n / (k * k);
cout << sum << endl;
fprintf(stderr, "time = %.2f, bits = %d\n", 1. * clock() / CLOCKS_PER_SEC, sizeof(int *) * 8); // stamp
return 0;
}