#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <algorithm>
#include <functional>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cctype>
#include <string>

using namespace std;

int main() {
  int n, m;
  cin >> n >> m;
  int a[m];
  for (int i = 0; i < m; i++) {
    cin >> a[i];
  }
  vector <int> x(n);
  for (int i = 0; i < n; i++) {
    x[n-1-i] = i+1;
  }
  for (int i = 0; i < m; i++) {
    int t = x[n-1-(a[i]-1)];
    x.erase(x.begin()+n-1-(a[i]-1));
    x.push_back(t);
    // for (int j = 0; j < n; j++) {
    //   std::cout << x[j] << " ";
    // }
    // std::cout << std::endl;
  }
  std::cout << x[n-1] << std::endl;
}