#include <iostream>
#include <sstream>
#include <math.h>
#include <stack>
#include <set>
#include <algorithm>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <cstdio>
#include <vector>
using namespace std;

#define INF (1 << 30)
#define INFLL (1LL << 60)

int main() {
	int yama[51];
	for(int i = 0;i < 51;i++){
		yama[i] = i;
	}
	int n,m,num;
	cin >> n >> m;
	for(int i = 0;i < m;i++){
		cin >> num;
		for(int j = num;j > 1;j--){
			swap(yama[j],yama[j-1]);
		}
	}
	cout << yama[1] << endl;
	return 0;
}