Bài 1. Viết chương trình tìm ước số chung lớn nhất, bội số chung nhỏ nhất của hai số tự nhiên a và b.

import java.util.Scanner;
 public class Main {
     public static int nhap()
    {
        Scanner input = new Scanner(System.in);
        boolean check= false;
                        int n=0;
                        while(!check){
                                    System.out.print(" ");
                                    try{
                                                n= input.nextInt();
                                                check= true;
                                    }catch(Exception e){
                                                System.out.println("Ban phai nhap so! hay nhap lai...");
                                                input.nextLine();
                                    }
                        }
                        return (n);
    }
    public static int UCLN(int a, int b){
                        while(a!= b){
                                    if(a>b) a= a-b;
                                    else b= b-a;
                        }
                        return (a);
            }
    public static void main(String[] args) {
        System.out.println("Nhap a");
                        int a = nhap();
                        System.out.println("Nhap b");
                        int b= nhap();
                        System.out.println("Uoc chung lon nhat cua "+a+" va "+b+" la: "+UCLN(a,b));
                        System.out.println("Boi chung nho nhat cua "+a+" va "+b+" la: "+((a*b)/UCLN(a,b)));
    }
 }