#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>

using namespace std;
int n;
int cnt =0;

int dfs(int a){
	if(a>n){return 0;}
	if(a==n){cnt+=1; return 0;}
	dfs(a+2);
	//a=a-2;
	dfs(a+1);
	a=a-1;
	return cnt;
}

int main() {

	cin>>n;
	cout<<dfs(0)<<endl;
}