为什么删掉第六行three=one+two；以后不能正常显示结果？

public class HelloWorld{

    public static void main(String[] args) {

   int one = 10 ;

        int two = 20 ;

        int three = 0 ;

        three=one+two;

        System.out.println("three=one+two==>"+three);

        three+=one;

        System.out.println("three=three+one==>"+three);

        three-=one;

        System.out.println("three=three-one==>"+three);

        three*=one;

        System.out.println("three=three*one==>"+three);

        three/=one;

        System.out.println("three=three=three/one==>"+three);

        three%=one;

        System.out.println("three=three%one==>"+three);