#include <algorithm>
#include <cstdio>
#include <iostream>
#include <string>
#include <vector>
#include <map>
#define rep(i, n) for (int i=0; i<n; ++i)
#define FOR(i, a, b) for (int i=a; i<b; ++i)
#define pb(x) push_back(x)
#define ll long long
#define ul unsigned long long
#define debug(x) cout  << #x << " : " << x << endl
#define out(x) cout << x
#define outl(x) cout << x << endl
#define int(n); int n; cin >> n;
#define llong(n); long long n; cin >> n;
#define s(s); string s; cin >> s;
#define in(a, n) for (int i = 0; i < n; ++i) cin >> a[i]
#define in2(a, m, n) for (int i = 0; i < m; ++i) for (int j = 0; j < n; ++j) cin >> a[i][j]
using namespace std;

const int inf =1500000000;
int main () {
  int(n); int(m);
  int a[n]; in(a, n);
  int c[n]; rep(i, n) c[i] = i;
  rep(i, m) {
    int tmp = c[0];
    c[0] = c[a[i] - 1];
    for (int j=a[i] -1; j>1; --j) {
      c[j]= c[j] -1;
    }
    c[1] = tmp;
  }
  outl(c[0]);
  
   return 0;
}