Help me in solving CLB002A problem

My issue

I don’t have understanding this problem.so please help me.

My code

#include <stdio.h>

int main() {
  
  // Delete __ (underscore) and add 20 at it's place
  printf("%d", __);
  
}

Learning course: Programming and Problem solving using C
Problem Link: https://www.codechef.com/learn/course/ciet-programming-c/CIETPC01/problems/CLB002A