trail

while True:
    value = int(raw_input())

    if value == 0: break
    while True:
        lista = map(int, raw_input().split())
        num = max(lista)
        aux = lista[:]
        if len(lista) == 1 and lista[0] == 0:
            print
            break

        passa = []
        agr_n = []
        while len(lista) != 0:
            if lista[-1] == num:
                passa.append(lista.pop(-1))
                num -= 1
            elif len(agr_n) >= 1 and agr_n[-1] == num:
                passa.append(agr_n.pop(-1))
                num -= 1
            else:
                agr_n.append(lista.pop(-1))
        if len(agr_n) >= 1 and len(passa) >= 1 and agr_n[-1]+1 == passa[0]:
            passa = agr_n + passa
        else: passa = passa + agr_n

        if passa == sorted(aux) or passa == sorted(aux, reverse= True): print "Yes"
        else: print "No"