from heapq import heappop, heappush

N, *A = map(int, open(0).read().split())

q = []
for i in range(N):
    if A[i] == i + 1:
        heappush(q, i)

while q:
    i = heappop(q)
    A[i] = 0
    for j in range(i):
        A[j] += 1
        if A[j] == j + 1:
            heappush(q, j)

if all(a == 0 for a in A):
    print('Yes')
else:
    print('No')