def perm_recursion(perm, remaining, depth, p):
    if depth + 1 == p:
        for i in remaining:
            perm[depth] = i
            yield perm
    else:
        for i in remaining:
            perm[depth] = i
            remaining.remove(i)
            perm_recursion(perm, remaining, depth + 1, p)
            remaining.add(i)


def perm_recursion(perm, remaining, depth, p):
    for i in remaining:
        perm[depth] = i
        if depth + 1 == p:
            yield perm
        else:
            remaining.remove(i)
            perm_recursion(perm, remaining, depth + 1, p)
            remaining.add(i)