#include<iostream>
using namespace std;
int main(){
	int card[51];
	int n, m; cin >> n >> m;
	for (int i = 0; i < n; i++) card[i] = i + 1;

	for (int i = 0; i<m; ++i){
		int a; cin >> a;
		for (int j = a - 2; j >= 0; --j){
			int t = card[j];
			card[j] = card[j + 1];
			card[j + 1] = t;
		}
	}
	cout << card[0] << endl;
	return 0;
}