using System;
using System.Collections.Generic;
class Program
{
static List<char> GetMissingAlphabetChars(string input) {
bool[] present = new bool[26];
// Normalize input: lowercase + keep only a..z
foreach (char c in input) {
char lower = char.ToLower(c);
if (lower >= 'a' && lower <= 'z') {
present[lower - 'a'] = true;
}
}
// Collect missing letters
var missing = new List<char>();
for (int i = 0; i < 26; i++) {
if (!present[i]) {
missing.Add((char)('a' + i));
}
}
return missing;
}
static void Main()
{
var missing = GetMissingAlphabetChars("C# Programming");
foreach (char c in missing) {
Console.WriteLine(c);
}
}
}
/*
run:
b
d
e
f
h
j
k
l
q
s
t
u
v
w
x
y
z
*/
