def check_correctness(lines):
    (ifndef_symbol, line_number) = get_ifndef_symbol(lines)
    if (line_number == (- 1)):
        return 'No #ifndef in file'
    (define_symbol, line_number) = get_define_symbol(lines)
    if (line_number == (- 1)):
        return 'No #define in file'
    index = [i for (i, s) in enumerate(lines) if ('#endif' in s)]
    if (len(index) == 0):
        return 'No #endif in file'
    return ''
def check_correctness(lines):
    (ifndef_symbol, line_number) = get_ifndef_symbol(lines)
    if (line_number == (- 1)):
        return 'No #ifndef in file'
    (define_symbol, line_number) = get_define_symbol(lines)
    if (line_number == (- 1)):
        return 'No #define in file'
    index = [i for (i, s) in enumerate(lines) if ('#endif' in s)]
    if (len(index) == 0):
        return 'No #endif in file'
    return 