import collections

def read_data():
    N = int(input())
    As = [int(input()) for i in range(N)]
    return N, As

def solve(N, As):
    if N == 1:
        if As[0] == 0:
            return [-1]
        else:
            return [0]
    result = [-1] * N
    freq = collections.Counter([a for a in As if a < N])
    free = [i for i in range(N) if i not in freq]
    most_com = freq.most_common()
    poss = [pos for pos, count in most_com] + free
    priority = [(0 if a not in freq else freq[a], i, a) for i, a in enumerate(As)]
    priority.sort()
    for pos in poss:
        idx = len(priority) - 1
        while priority[idx][2] == pos:
            idx -= 1
            if idx < 0:
                return [-1]
        result[priority[idx][1]] = pos
        del priority[idx]
    return result

N, As = read_data()
answer = solve(N, As)
for ans in answer:
    print(ans)