problem in return statement

import java.io.*;
public class CandidateCode
{
public static String JudgementDay(int input1,int input2)
{
int t=0,n=0,r=3,m=1,pm=0;
int b=34;

  int k=100000007;
 n=input1*input2;
 for(int i=1;i<=n;i++)
  {
    
    t=m;
    
    m=(r+2*pm)%k;
    r=(r+3*pm)%k;
    pm=(5*t)%k;
    
    
  }
   return(r+""+m+""+pm);
}

i want output like 18#13#15…no S.o.p statements to be used so tell the syntax in return statements

i tried for return(r+""+m+""+pm) my output 181513
smiliarly (r+""+m+""+pm)output is 18$15#13
but for # it is giving error.plss suggest me the solution

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