#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
using namespace std;

long long MOD = 1000000007;

int main() {
    
    int N,M;
    cin >> N >> M;
    vector<int> A(N);
    for ( int i = 0; i < N; i++ ) { A[i] = N-i; }
    for ( int i = 0; i < M; i++ ) {
        
        int a;
        cin >> a;
        a = N-1-(a-1);
                
        int t = A[a];
        
        A.erase( A.begin() + a );
        A.push_back(t);
    }
    
    cout << A[N-1] << endl;
    
    return 0;
}