Example

Input

5 3
4
2
5


Output

5
2
4
1
3
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 998244353

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)


def main():
    rr = []

    while True:
        n,m = LI()
        a = [I() for _ in range(m)][::-1]
        f = [None] * (n+1)
        for c in a:
            if f[c] is None:
                f[c] = 1
                rr.append(c)

        for c in range(1,n+1):
            if f[c] is None:
                rr.append(c)

        break



    return '\n'.join(map(str, rr))


print(main())


