#include <fstream>

using namespace std;

ifstream fi("kfib.in");
ofstream fo("kfib.out");

const int mod = 666013;

int main()
{
	long long a, b, c;
	int i, n;
	
	fi>>n;
	
	a = 0;
	b = 1;
	i = 1;
	
	while(i < n)
	{
		c = a + b;
		a = b;
		b = c;
		
		i++;
	}
	
	fo<<c;
}