#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <ostream>
#include <queue>
#include <stack>
#include <string>
#include <vector>
#define INF 1000000000
#define rep(i,a,b) for (int i=(a);i<(b);i++)
#define rev(i,a,b) for (int i=(a)-1;i>=b;i--)
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef queue<int> qi;
typedef queue< pair<int, int> > qpii;
typedef vector<int> vi;
typedef vector<int, int> vii;
typedef vector<string> vs;
typedef vector< pair<int, int> > vpii;
int dx[4] = { 0, 1, 0, -1 };
int dy[4] = { 1, 0, -1, 0 };

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

  int n, m;
  cin >> n >> m;
  vi c(n);
  rep(i,0,n) c[i] = i+1;
  rep(i,0,m) {
    int num;
    cin >> num;
    int tmp = c[num-1];
    rev(j,num,1) c[j] = c[j-1];
    c[0] = tmp;
  }
  cout << c[0] << endl;

	return 0;
}