def main():
    n = int(input())
    A = list(map(int, input().split()))
    l = n
    r = 0
    X = [0] * (n+2)
    for i in range(n):
        a = A[i]
        if 1 < a:
            a = a-1
            X[max(0, i-a+1)] += 1
            X[min(n, i+a)] -= 1
    for i in range(n):
        X[i] += X[i-1]
        if not X[i]:
            return "Yes"
    return "No"
print(main())