约数研究——洛谷1043

#include <iostream>

using namespace std;

const int N = 100010;

int main()
{
    int n;
    scanf("%d", &n);

    int res = 0;
    for (int i = 1; i <= n; i ++ ) res += n / i;
    printf("%d\n", res);

    return 0;
}