#include <stdio.h>
#define max 1000000
int main()
{long long n,t[max],i;
    freopen("12perm.in","r",stdin);
    freopen("12perm.out","w",stdout);
    scanf("%lld",&n);
    if(n==1) {printf("1");return 0;}
    else if(n==2) {printf("2");return 0;}
    else if(n==3) { printf("6");return 0;}
    else if(n==4) {printf("12");return 0;}
    else
{t[1]=1;t[2]=2;t[3]=6;t[4]=12;
    for(i=5;i<=n;i++)
    t[i]=t[i-1]+t[i-3]+2*(i-2);}
   printf("%lld\n",t[i]);
   return 0;
}