#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
#define rep(i,n) for(int i = 1; i < (n); i++)

int main(){
    int n; cin >> n;
    vector<int>s(n);
    rep(i,n){ s[i] = i; }

    int m; cin >> m;
    int a;
    rep(i,m){
        cin >> a;
        s.erase(s.begin() + (a+1));
        s.insert(s.begin(),a);
    }
    cout << s[0] << endl;

    return 0;
}