#include <iostream.h>
long fib(long n)
{
	if(n == 1 || n == 2)
		return 1;
	else
		return fib(n-1) + fib(n-2);
}

long fibiter(long n)
{
	if(n == 1 || n == 2)
		return 1;
	long prev1 = 1, prev2 = 1;
	for(long i = 3, current = 1; i <= n; i++)
	{
		current = prev1 + prev2;
		prev2 = prev1; prev1 = current;
	}
	return current;
}

void main()
{
	cout << fibiter(35);
}