#include <stdio.h>
long int arr[1000002];
void array ()
{
long int k=0,i;
arr[3]=0;
for( i = 4; i <= 1000000; i++)
{
k = k + ((i-2)/2);
arr[i] = arr[i-1] + k;
}
}
int main()
{
//array();
long int n;
array();
while(scanf("%ld",&n) && n >= 3)
printf("%ld\n",arr[n]);
return 0;
}
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