with open('data.txt', 'r', encoding='utf-8') as input_file:
    lines = input_file.readlines()

upper_case_lines = [line.upper() for line in lines]

with open('output.txt', 'w', encoding='utf-8') as output_file:
    output_file.writelines(upper_case_lines)

print("Данные успешно преобразованы и записаны в output.txt.")