import sys

def input(): return sys.stdin.readline().strip()
def list2d(a, b, c): return [[c] * b for i in range(a)]
def list3d(a, b, c, d): return [[[d] * c for k in range(b)] for i in range(a)]
def list4d(a, b, c, d, e): return [[[[e] * d for k in range(c)] for k in range(b)] for i in range(a)]
def ceil(x, y=1): return int(-(-x // y))
def INT(): return int(input())
def MAP(): return map(int, input().split())
def LIST(N=None): return list(MAP()) if N is None else [INT() for i in range(N)]
def Yes(): print('Yes')
def No(): print('No')
def YES(): print('YES')
def NO(): print('NO')
sys.setrecursionlimit(10**9)
INF = 10**19
MOD = 10**9 + 7
EPS = 10**-10

N = INT()
A = LIST()

if sum(A[1:]) == 0:
    Yes()
    exit()

ended = 0
cnt = 0
for i in range(1, N):
    if ended:
        if A[i] != 0:
            No()
            exit()
    else:
        if A[i] == i*2-1:
            cnt += 1
        elif A[i] == 0:
            if cnt < A[0]-1:
                No()
                exit()
            ended = 1
        else:
            No()
            exit()
Yes()