711. Multiply Two Numbers Without * Operator

Given two integers a and b, return their product a * b without using the multiplication operator. Use recursion (and addition/subtraction) only. Your function must correctly handle negative numbers and zero.

Input: Two integers a and b separated by a comma.

Output: Return an integer equal to a * b.

Examples

Input: 3, 4
Output: 12
Explanation: Add 3 four times: 3+3+3+3 = 12.

Input: -5, 6
Output: -30
Explanation: Result is negative because exactly one operand is negative.

Input: 0, 100
Output: 0
Explanation: Anything times zero is zero.

Constraints

• -1000 <= a, b <= 1000

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