Example

Input

5 3
4
2
5


Output

5
2
4
1
3
#include<bits/stdc++.h>
using namespace std;

#define int long long
typedef vector<int>vint;
typedef pair<int,int>pint;
typedef vector<pint>vpint;
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
#define all(v) (v).begin(),(v).end()
#define each(it,v) for(__typeof((v).begin()) it=(v).begin();it!=(v).end();it++)
#define pb push_back
#define fi first
#define se second
template<typename A,typename B>inline void chmin(A &a,B b){if(a>b)a=b;}
template<typename A,typename B>inline void chmax(A &a,B b){if(a<b)a=b;}

int N,M;
bool used[222222];
signed main(){
    cin>>N>>M;
    vint v(M);rep(i,M)cin>>v[i],v[i]--;
    reverse(all(v));rep(i,N)v.pb(i);
    rep(i,v.size()){
        if(used[v[i]])continue;
        used[v[i]]=true;
        printf("%lld\n",v[i]+1);
    }

    return 0;
}