#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
#define ITER(c)             __typeof__((c).begin())
#define FOREACH(it, c)      for (ITER(c) it=(c).begin(); it != (c).end(); ++it)
#define REP(i, n)           for(int(i)=0;(i)<(n);++(i))
#define RREP(i, n)          for(int(i)=(n)-1;(i)>=0;--(i))
const int MOD = (int)1e9+7;

int main(){
    int N,M; cin >> N >> M;
    int A[100100];
    REP(i,M){
        cin >> A[i];
    }
    VI v;
    REP(i,N){
        v.push_back(i+1);
    }
    REP(i,M){
        int k = v[A[i]-1];
        RREP(j,A[i]-1){
            v[j+1] = v[j];
        }
        v[0] = k;
    }
    cout << v[0] << endl;
}