#include <bits/stdc++.h>

using namespace std;

int main(){
	int n;
	scanf("%d",&n);
	double ans = 0;
	for (int i = 1000000; i >= n; --i) {
	    ans += riemann_zeta(i) - 1;
	}
	long a = (long)(1000000 * ans);
	cout << a << endl;
	return 0;
}