#include <iostream>
#include <iomanip>
#include <vector>

typedef long long ll;

int main(void)
{
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);
  std::cout << std::fixed << std::setprecision(8);
  ll n, m;
  std::cin >> n >> m;
  std::vector< int > deck(n);
  for (int i = 0; i < n; ++i) deck[i] = i+1;
  for (ll i = 0; i < m; ++i) {
    int ai;
    std::cin >> ai;
    int dai = deck[ai-1];
    for (int j = ai-1; j >= 1; --j) deck[j] = deck[j-1];
    deck[0] = dai;
  }
  std::cout << deck[0] << std::endl;
  return 0;
}