#include <cstdio>

int main()
{
    int n,i,j,brtoc;
    scanf("%d",&n);
    brtoc=0;
    for (i=0;i<=n;++i) for (j=i;j<=n;++j) { brtoc = brtoc+i; brtoc = brtoc+j; }
    printf("%d",brtoc);
    return 0;
}