phones_filter.py

f = open("output.txt","w")

with open("input.txt", 'r') as fh:
    for line in fh:
        name, phone = line.split(" ")
        phone = phone.strip()
        numbers = {}
        for num in phone:
            if num in numbers:
                numbers[num] += 1
            else:
                numbers[num] = 1
        if len(numbers) <= 3:
            f.write(name + " " + phone + "\n")
f.close()