백준 16953 c++

#include <iostream>

using namespace std;

int find_result(long long A, long long B)
{
	int count = 0;

	while (B >= A)
	{
		if (B % 10 == 1)
		{
			B = (B - 1) / 10;
		}
		else
		{
			if ((B % 10) % 2 == 1)
			{
				return -1;
			}
			else
			{
				B = B / 2;
			}
		}
		count++;
		if (B == A)
		{
			count++;
			return count;
		}
		else
		{
			;
		}
	}

	return -1;
}

int main(void)
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	
	long long A, B;

	cin >> A >> B;
	cout << find_result(A, B) << "\n";

	return 0;
}