Minimum Operations to Make the Integer Zero

Given num1 and num2, you may repeatedly subtract values of the form 2^i + num2 (i in [0,60]); find the minimum number of such operations to make num1 exactly 0, or return -1 if impossible. The core challenge is deciding if and how num1 can be expressed as a nonnegative integer combination of the special "coin" set {2^i + num2} and minimizing the count.