import sys
def replace_digit_with_X_and_remove_duplicates(data, position):
numbers = data.split()
unique_numbers = []
seen = set()
for num in numbers:
if len(num) == 4:
if num[:position-1] + num[position:] not in seen:
seen.add(num[:position-1] + num[position:])
unique_numbers.append(num[:position-1] + 'X' + num[position:])
elif len(num) != 4:
print(f"Warning: {num} is not a 4-digit number.", file=sys.stderr)
result = ' '.join(unique_numbers)
return result, len(unique_numbers)
data = sys.stdin.read()
position = 1
modified_data, count = replace_digit_with_X_and_remove_duplicates(data, position)
print(f"组数: {count}")
print(modified_data)