Given two strings representing two complex numbers. You need to return a string representing their multiplication. Note i2 = -1 according to the definition. Example 1: ``` Input: "1+1i", "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: "1+-1i", "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. ``` Note: * The input strings will not have extra blank. * The input strings will be given in the form of a+bi, where the integer a and b will both belong to the range of [-100, 100]. And the output should be also in this form. ``` var a1 = a.split("+"); var b1 = b.split("+"); var a2 = a1[1].split("i"); var b2 = b1[1].split("i"); console.log(a1,a2); return a1[0]*b1[0]-a2[0]*b2[0] + "+" + (a1[0]*b2[0]+a2[0]*b1[0])+"i"; ```