import sys
input = sys.stdin.readline

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

LIST=[0]*(N+5)

for i in range(N):
    x=N-A[i]

    if i-x<N:
        LIST[max(i-x,0)]+=1

    if i+x+1>=0:
        LIST[min(i+x+1,N+4)]-=1

for i in range(1,len(LIST)):
    LIST[i]+=LIST[i-1]

if max(LIST)==N:
    print("Yes")
else:
    print("No")