#include <bits/stdc++.h>
typedef long long LL;
#define SORT(c) sort((c).begin(),(c).end())

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

using namespace std;
int main(void)
{
  int n;
  cin >> n;
  vector<int> a;
  a.resize(n);
  REP(i,n) cin >> a[i];
  int answer=n;
  REP(i,n)
    if(a[n-1-i]==answer) --answer;
  cout << answer << endl;
  
  return 0;
}