Help me in solving CLB050 problem

help
,
1

My issue

I DIDNOT UNDESTAND THE PROBLEM

My code

#include <stdio.h>

int main() {
    char var[] = "String";
    printf("%c", var[ _ ])
    printf("%c", var[ _ ])
    printf("%c", var[ _ ])
}

Learning course: Programming and Problem solving using C
Problem Link: https://www.codechef.com/learn/course/ciet-programming-c/CIETPC12/problems/CLB050