#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int N, M;
  cin >> N >> M;
  vector<int> A(N);
  iota(A.begin(), A.end(), 0);
  vector<int> idx(N);
  iota(idx.begin(), idx.end(), 0);
  int cur = -1;
  for (int i = 0; i < M; i++) {
    int x;
    cin >> x;
    x--;
    A[idx[x]] = cur--;
    sort(idx.begin(), idx.end(), [&](int a, int b) { return A[a] < A[b]; });
  }
  cout << idx[0] + 1 << '\n';
  return 0;
}