A complex number can be represented as a string on the form `"`

where:**real**+**imaginary**i"

`real`

is the real part and is an integer in the range`[-100, 100]`

.`imaginary`

is the imaginary part and is an integer in the range`[-100, 100]`

.`i`

.^{2}== -1

Given two complex numbers `num1`

and `num2`

as strings, return *a string of the complex number that represents their multiplications*.

**Example 1:**

Input:num1 = "1+1i", num2 = "1+1i"Output:"0+2i"Explanation:(1 + i) * (1 + i) = 1 + i2 + 2 * i = 2i, and you need convert it to the form of 0+2i.

**Example 2:**

Input:num1 = "1+-1i", num2 = "1+-1i"Output:"0+-2i"Explanation:(1 - i) * (1 - i) = 1 + i2 - 2 * i = -2i, and you need convert it to the form of 0+-2i.

**Constraints:**

`num1`

and`num2`

are valid complex numbers.

class Solution {
public String complexNumberMultiply(String num1, String num2) {
}
}