Maximum_69_Number.py

def m(num):
    six_index = 0
    str_num = str(num)

    for index in range(len(str_num)):
        if str_num[index] == '6':
            six_index = index
            break

    return int(
        str_num[:six_index] +
        '9' +
        str_num[six_index + 1:]
    )
print(m(int(input())))