Easy Solution
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:
        if n==k:
            return 0
        if k>n:
            return -1
        k1=bin(n)[2:]
        k2=bin(k)[2:]
        max_length = max(len(k1), len(k2))
        k1 = k1.zfill(max_length)
        k2 = k2.zfill(max_length)
        c=0
        for i in range(max_length):
            if k1[i]=='0' and k2[i]=='1':
                return -1
            elif k1[i]=='1' and k2[i]=='0':
                c+=1
        return c
```
['Python3']