from datetime import datetime, timedelta


def get_last_friday(a: str) -> str:
    date = datetime.strptime(a, "%m/%Y")
    next_month = date.replace(month=date.month % 12 + 1, day=1)

    last_day = next_month - timedelta(days=1)

    while last_day.weekday() != 4:
        last_day -= timedelta(days=1)

    return last_day.strftime("%d.%m.%Y")