#include <stdio.h>
#include <openssl/bn.h>
int main(int ac, char **av)
{
	BIGNUM l1, l2, l3;
	int n = atoi(av[1]);
	int state;
	char *result;

	BN_init(&l1);
	BN_init(&l2);
	BN_init(&l3);
	BN_zero(&l1);
	BN_one(&l2);
	BN_zero(&l3);
	state = 1;
	do {
		switch (state) {
		case 1:
			BN_add(&l3, &l2, &l1);
			state = 2;
			break;
		case 2:
			BN_add(&l1, &l3, &l2);
			state = 3;
			break;
		case 3:
			BN_add(&l2, &l1, &l3);
			state = 1;
			break;
		}
	} while (--n != 0);
	switch (state) {
	case 1:
		result = BN_bn2dec(&l2);
		break;
	case 2:
		result = BN_bn2dec(&l3);
		break;
	case 3:
		result = BN_bn2dec(&l1);
		break;
	}
	printf("%s\n", result);
}