sol.cpp

#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <queue>

using namespace std;

const int N = 500;
const long long mod = 1e9 + 7;

int main(){
  int n, p; cin >> n >> p;
  set<int> s; 
  // solve the problem in reverse order 
  // suppose you already have all the elements of the list
  // and a student comes, means we remove it from the set of available students
  for(int i = 1; i <= n; i++) s.insert(i);
  for(int i = 0; i < p; i++){
    int cur; cin >> cur;
    auto it = s.find(cur); // find the current
    s.erase(it); // remove it
    cout << *s.begin() << endl; // get the minimum available student
  }
  return 0;
}