def exchange(programs, move):
    """Exchange, written xA/B, makes the programs at positions A and B swap places."""
    a, b = [int(i) for i in move[1:].split('/')]
    programs_ = list(programs)

    tmp = programs_[b]
    programs_[b] = programs_[a]
    programs_[a] = tmp

    return ''.join(programs_)