Class_A.java

package cla;
//Import 省略
public class Class_A{
 public void Start(){
   System.out.printIn("Success!!");
 }
}

Class_B.java

package clb;
//Import 省略

  public class Class_A{
  public void Start(){
  Syustem.out.printIn("Success!!");
  }
  }

Class_C.java

package clc;

public class Class_C {
  public void main(string[] args){
  
  }
}