import java.util.*;
class Ideone {
	public static void main (String[] args) {
		System.out.println(Arrays.toString(
          "2+3*i + 1-4*i + -2*i".split("(\\*i)? *((?<=\\d)(?=-)|-(?!\\d)|\\+|$) *")));
        System.out.println(Arrays.toString(
          "2+3*i - 1-4*i - -2*i".split("(\\*i)? *((?<=\\d)(?=-)|-(?!\\d)|\\+|$) *")));
    }
}