N = int(input())
A = list(map(int, input().split()))

while A != [0] * N:
    for i in range(N):
        if A[i] == i + 1:
            A[i] = 0
            for j in range(i):
                A[j] += 1
            break
    else:
        print('No')
        exit()
print('Yes')