#include <bits/stdc++.h>
#include <atcoder/all>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace atcoder;
using namespace __gnu_pbds;
using ll=long long;
using ld=long double;
using vll=vector<ll>;
using pll=pair<ll,ll>;

using mint=modint;

template<class K,class V>
using ordered_map=tree<K,V,less<K>,rb_tree_tag,tree_order_statistics_node_update>;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
    
    ordered_map<ll,ll> mp;
    ll N,M,t=0;
    cin>>N>>M;
    for(int i=1;i<=N;++i)mp.insert({i,i});
    for(int i=1;i<=M;++i){
        ll A;
        cin>>A;
        auto it=mp.find_by_order(A-1);
        ll key=it->first;
        ll val=it->second;
        mp.erase(key);
        mp.insert({t,val});
        t--;
    }
    auto it=mp.find_by_order(0);
    cout<<it->second<<endl;
}