Fascinating Number

//This code was contributed by @VividhPandey003
import java.util.*;
public class fascinatingNumber
{   
    public static void main(String args[])
    {   
        Scanner sc=new Scanner(System.in);
        int m,n=0; int k=0; int no1,no2,no3=0; int len=0;
        String word="";String st="";String str="123456789";
        char ch='\0'; char chr='\0',t='\0';           
        System.out.println("Enter a range");
        m=sc.nextInt();
        n=sc.nextInt();
        if(m>99&&n<10000 && m<n)            
        {   
            System.out.println("The fascinating numbers are:");             
            for(int i=m;i<=n;i++)              
            { 
                word=""; st="";
                no1=i*1;
                no2=i*2;
                no3=i*3;
                word=Integer.toString(no1)+Integer.toString(no2)+Integer.toString(no3);
                char c[]=word.toCharArray();            
                len=c.length;
                for(int j=0;j<len-1;j++)
                { 
                    ch=c[j];
                    chr=c[j+1];
                    if(ch>chr)
                    { 
                        t=ch;           
                        ch=chr;
                        chr=t;c[j+1]=chr;c[j]=ch;
                        j=-1;
                    }
                }   //array is sorted now
                st= String.valueOf(c);
                if(Long.valueOf(st)==123456789)         
                {
                    k++;
                    System.out.print(i +"   ");
                }
            }
            System.out.println();                 //optional
            System.out.println("frequency="+ k);
        }
        else 
            System.out.println("INVALID INPUT");
    }
}