#include <iostream>
#include <math.h>
#include <string>
#include <algorithm>
using namespace std;
int kaijo(long long n){
	long long ans = 1;
	if (n != 0){
		for (long long i = 0; i < n; i++){
			ans *= (n - i);
		}
	}
	else{
		ans = 1;
	}
	return ans;
}
int permtation(long long n,long long r){
	long long ans = 1;
	if (r != 0){
		for (long long i = 0; i < r; i++){
			ans *= (n - i);
		}
	}
	else{
		ans = 1;
	}
	return ans;
}

int main(){
	long long n;
	long long cnt1 = 0;
	long long cnt2 = 0;
	long long cntp = 0;
	cin >> n;
	cnt2 = n / 2;
	if ((n / 2) * 2 == n){
		cnt1 = 0;
	}
	else{
		cnt1 = 1;
	}
	while (1){
		if (cnt2 == 0) {
			cntp += 1;
			break;
		}
		if (cnt2 > cnt1){
			cntp += permtation(cnt2 + cnt1, cnt1) / kaijo(cnt1);
		}
		else{
			cntp += permtation(cnt2 + cnt1, cnt2) / kaijo(cnt2);
		}
		cnt2 -= 1;
		cnt1 += 2;
	}
	cout << cntp << endl;
	return 0;
}