Badstr

#include <stdio.h>
#include <iostream>
using namespace std;
long long fib(int n) {
	long long f1, f2, f3;
	f1=f2=f3=1;
	for(int i=2; i<n; i++) {
		f3=f2;
		f2=f1;
		f1=f2+f3;
	}
	return f1;
}

int main() {
    freopen("badstr.in", "r", stdin);
    freopen("badstr.out", "w", stdout);
	int c;
    cin>>c;
    cout<<fib(c*2+2);
    return 0;
}