#include <stdio.h>

int main(void) {
int a[33],b,sum=0;
a[0]=2;a[1]=-1;
for(b=2;b<=32;b++)
{a[b]=-a[b-1]+a[b-2]+2;
if(b%4==0)
sum=a[b]+sum;}
printf("%d",sum+2);
return 0;
}