Unique Answer
IntuitionApproachComplexity
Time complexity:

Space complexity:
Code
# Intuition
<!-- Describe your first thoughts on how to solve this problem. -->

# Approach
<!-- Describe your approach to solving the problem. -->

# Complexity
- Time complexity:
<!-- Add your time complexity here, e.g. $$O(n)$$ -->

- Space complexity:
<!-- Add your space complexity here, e.g. $$O(n)$$ -->

# Code
```python3 []
class Solution:
    def minChanges(self, n: int, k: int) -> int:
        nbit = str("{0:b}".format(n))
        kbit = str("{0:b}".format(k))
        l = max(len(nbit), len(kbit))
        nbit = nbit.zfill(l)
        kbit = kbit.zfill(l)
        count = 0
        for i in range(l):
            if nbit[i] == "1" and kbit[i] == "0":
                count += 1
            if nbit[i] == "0" and kbit[i] == "1":
                return -1
        return count

```
['Python3']