class Whileloop
{
    public static void main (String args[])
    {
        int i = 1;
        while (i <= 4)
        {
            System.out.print("n");
            int j = 1;
            while (j <= i)
            {
                System.out.print(j);
                j++;
            }
            i++;
        }
    }
}

do{
          //do here
       }while(booleanExpression);

class Tester
    {
       public static void main (String args[]){

          int i=1;
          do{                          //block started with out checking condition
         System.out.print("n");
         int j=1;
         do {                       //inner loop starts
           System.out.print(j);
           j++;
           }while(j<=i);             //condition check for inner loop
           i++;
          }while(i<=4);             //condition check for outer loop
        }
    }

int i=1;
    do {
        System.out.print("n");
        int j=1;

        do {
            System.out.print(j);
            j++;
        } while (j<=i);

        i++;
     } while(i <= 4);
  }

while(condition)
    {
      //code
    }

do
    {
       //code
    }while(condition);