def verifica(a,b):
    sx = verificaComodo(left(a),b,1)
    dx = verificaComodo(right(a),b,1)
    return sx or dx

def verificaComodo(a,b,livello):

    t = trova(info(a),b,livello,0)
    if t == True:
        return True
    else:
        t_sx = False
        t_dx = False

        if not isNull(left(A)):
            t_sx = verificaComodo(left(a),b, livello+1)

        if not isNull(right(A)):
            t_dx = verificaComodo(right(a),b,livello+1)

        return t_sx or t_dx

def trova(infoA,b,livello,current):
    if isNull(b) or livello <= current:
        return False

    if info(b) == infoA:
        return True

    return trova(infoA,left(b),livello, current + 1) or trova(infoA,right(b),livello, current + 1)