#include <math.h>
#include <string.h>
#include <iostream>

int fib(int n) {
	if (n == 0) {
		return 1;
	} else if (n == 1) {
		return 1;
	} else {
		return fib(n-1) + fib(n-2);
	}
}
int main(int argc, char **argv) {
	printf("%d\n", fib(atoi(argv[1])));
	return 0;
}