#include <stdio.h>

int main()
{
    int n;
    int c;
    int v = 0;
    scanf("%d",&n);
    for (int i = 1;i <= n;i++) {
        c = 0;
        for (int j = 1;j <= n;j++) {
            if (i % j == 0)c++;
            if (j == n && c == 2) v += i;
        }
    }
    printf("%d\n",v);
}