Number Pattern 2 by do while loop

Code Box by do while loop
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/*program to print number pattern by do while loop

  1
  12
  123
  1234
  12345

*/

class npat2do
{
public static void main(String a[])
{
int n,i,j;
i=1;
n=Integer.parseInt(a[0]);

do
{j=1;
        do
        {
        System.out.print(j);
        j++;
 }
 while(j<=i);

System.out.print("\n");
i++;
}
while(i<=n);

}
}