#include<iostream>
#include<cstdio>
using namespace std;
int a,b=0;
int now=3,ji;
int all[1001];
int shu(int a)
{
    for(int i=6;i<=a;i+=2)
    {
    	if(ji==2)
    	{
    		now+=2;ji=0;
		}
    	all[i]=all[i-1]+all[i-now];
    	all[i+1]=all[i];
    	ji++;
	}
}
int main()
{
	freopen("nums.in","r",stdin);
	freopen("nums.out","w",stdout);
	scanf("%d",&a);
	all[2]=2;all[3]=2;all[4]=4;all[5]=4;
	if(a<=5)
	{
		printf("%d",all[a]);return 0;
	}
	shu(a);
	printf("%d",all[a]);
	return 0;
}