#include <algorithm>
#include <iostream>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <cmath>
#include <stack>
using namespace std;

int main() {
	int N,M;
	cin >> N >> M;
	int cards[51] = {0};
	int cards_s[51] = {0};

	for (int i = 0;i <=N;i++){
		cards[i] = i;
	}

	for (int i = 0;i < M;i++){
		int c;
		cin >> c;

		for (int j = 0;j <=N;j++){
			cards_s[j] = cards[j];
		}

		cards_s[1] = cards[c];
		for (int j = 2;j<=c;j++){
			cards_s[j] = cards[j-1];
		}

		for (int j = 0;j <=N;j++){
			cards[j] = cards_s[j];
		}
	}
	cout << cards[1] << endl;
	return 0;
}