Answer:
The program in C is as follows:
#include <stdio.h>
int main(){
 int n;
 scanf("%d", &n);
 if(n<11 || n>100){
 printf("Input must be between 11 - 100"); }
 else{
 while(n%11 != 0){
 printf("%d ", n);
 n--; }
 printf("%d ", n); }
 return 0;
}
Step-by-step explanation:
The existing template can not be used. So, I design the program from scratch.
This declares the number n, as integer
 int n;
This gets input for n
 scanf("%d", &n);
This checks if input is within range (11 - 100, inclusive)
 if(n<11 || n>100){
The following prompt is printed if the number is out of range
 printf("Input must be between 11 - 100"); }
 else{
If input is within range, the countdown is printed
 while(n%11 != 0){ ----This checks if the digits are identical using modulus 11
Print the digit
 printf("%d ", n);
Decrement by 1
 n--; }
This prints the last expected output
 printf("%d ", n); }