The easiest solution (beat 100%)
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
```golang []
func minChanges(n int, k int) int {
    if k & (n-k) > 0{
        return -1
    }
    ans := 0
    n -= k

    for n > 0{
        now := n % 2
        if now == 1{
            ans += 1
        }
        n /= 2
    }
    return ans
}
```
['Bit Manipulation', 'Go']