#include <cstdio>

int n, dt[100] = { 1, 1 };

int main()
{
    int T;
    for(int prob = 1 ; prob <= 30 ; prob++ )
    {
        char in[110], out[110];
        sprintf(in, ".%d.in", prob); sprintf(out, ".%d.out", prob);
        freopen(in,"r",stdin); freopen(out,"w",stdout);
    scanf("%d", &n);
    for(int i = 2 ; i <= n ; i++ )
        dt[i] = dt[i-1] + 2*((i+1)/2);
    printf("%d\n", dt[n]);
    }
}