Staircase Pattern

You are given a positive integer ( n ). Your task is to print a right-aligned staircase pattern with ( n ) steps. Each step is represented by underscores (( _ )) and preceded by spaces to ensure alignment to the right.

If the input is not a positive integer, the program should produce no output.

inputFormat

The input consists of a single line containing an integer ( n ).

outputFormat

Output the staircase pattern for ( n ) steps. The ( i )-th line should contain ( n - i ) spaces followed by ( i ) underscores (( _ )). There should be no extra spaces or newlines at the end.## sample

4

   _
__

____