def decode_message(s):
    decoded = ""
    for i in range(0, len(s), 2):
        pair = s[i:i+2]
        ascii_val = int(pair)
        char = chr(ascii_val)
        if char.isalpha():
            decoded += char
        else:
            return "Invalid Input"
    return decoded

# Example usage
print(decode_message("656565"))  # Output: AAA
print(decode_message("657072"))  # Output: AFH
print(decode_message("123456"))  # Output: Invalid Input