Previous and next letter (Editorial)

Let $c$ be the input character. Print the characters $c-1$ and $c+1$.

Algorithm implementation

Read the input symbol $c$.

scanf("%c", &c);

Print the symbols c - 1 and c + 1.

printf("%c %c\n", c - 1, c + 1);

Python implementation

Read the input symbol $c$.

c = input()

Compute and print the symbols prev = c - 1 and next = c + 1.

prev = chr(ord(c) - 1)
next = chr(ord(c) + 1)
print(prev, next)