Example

Input

5 3
4
2
5


Output

5
2
4
1
3
#include "iostream"
#include "climits"
#include "list"
#include "queue"
#include "stack"
#include "set"
#include "functional"
#include "algorithm"
#include "string"
#include "map"
#include "unordered_map"
#include "unordered_set"
#include "iomanip"
#include "cmath"
#include "random"
#include "bitset"
#include "cstdio"
#include "numeric"
#include "cassert"
#include "ctime"

using namespace std;

constexpr long long int MOD = 1000000007;
//constexpr int MOD = 1000000007;
//constexpr int MOD = 998244353;
//constexpr long long int MOD = 998244353;
constexpr double EPS = 1e-12;

//int N, M, K, T, H, W, L, R;
long long int N, M, K, T, H, W, L, R;



int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	cin >> N >> M;
	vector<int>used(N + 1,-1);
	vector<int>v(M);
	for (auto &i : v)cin >> i;
	vector<int>ans;
	for (int i = M - 1; i >= 0; i--) {
		if (used[v[i]] == -1) {
			ans.push_back(v[i]);
			used[v[i]] = i;
		}
	}
	for (int i = 1; i <=N; i++) {
		if (used[i] == -1)ans.push_back(i);
	}
	for (auto i : ans)cout << i << endl;
}
