Example

Input

5 3
4
2
5


Output

5
2
4
1
3
n, m =  map(int, input().split())
e = [int(input()) for i in range(m)]
used = [False]*n
e.reverse()
ans = []
for x in e:
    if not used[x-1]:
        ans.append(x)
        used[x-1] = True
for i in range(n):
    if not used[i]:
        ans.append(i+1)
for x in ans:
    print(x)
