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[200000];

signed main(){
    cin>>N>>M;
    vint q(M);
    rep(i,M)cin>>q[i],q[i]--;
    for(int i=M-1;i>=0;i--){
        int a=q[i];
        if(used[a])continue;
        used[a]=true;
        printf("%lld\n",a+1);
    }
    rep(i,N)if(!used[i])printf("%lld\n",i+1);
    return 0;
}