#include <stdio.h>

#if 0
int main()
{
	long long a = 1;
	long long b = 1;
	printf("long long table[] = {\n");
	printf("1, 1, ");
	for (int i = 2; i <= 50; ++i)
	{
		long long c = a + b;
		printf("%lld, ", c);
		a = b;
		b = c;
	}
	printf("\n};");
	return 0;
}
#else
long long table[] = {
1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946, 17711, 28657, 46368, 75025, 121393, 196418, 317811, 514229, 832040, 1346269, 2178309, 3524578, 5702887, 9227465, 14930352, 24157817, 39088169, 63245986, 102334155, 165580141, 267914296, 433494437, 701408733, 1134903170, 1836311903, 2971215073, 4807526976, 7778742049, 12586269025, 20365011074, 
};
int main()
{
	char buf[8];
	int n;
	size_t read_count = fread(buf, sizeof(char), sizeof(buf), stdin);
	if (read_count == 2)
	{
		n = buf[0] - '0';
	}
	else
	{
		n = (buf[0] - '0') * 10 + (buf[1] - '0');
	}
	printf("%lld", table[n]);
	return 0;
}
#endif