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

int main(){
	int n;
	int cnt1 = 0;
	int 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;
		}
		cntp += kaijo(cnt2 + cnt1) / (kaijo(cnt1)*kaijo(cnt2));
		cnt2 -= 1;
		cnt1 += 2;
	}
	cout << cntp << endl;
	return 0;
}