n = int(input())
A = list(map(int, input().split()))
A.sort()
cnt = [0] * (10 ** 5 + 1)
for a in A:
    cnt[a] += 1

tot = 0
for i in range(10 ** 5):
    tot += cnt[i]
    if cnt[i] == 0:
        print(i)
        break
    elif cnt[i] == 1:
        if tot == n:
            print(i)
        else:
            print(i + 1)
        break