#include <bits/stdc++.h>
using namespace std;

int main() {
  int N;
  cin >> N;
  vector<int> A(N);
  for (int i = 0; i < N; i++) cin >> A.at(i);
  int cnt = 0, n = N;
  for (int i = N - 1; i >= 0; i--) if (A.at(i) == n) cnt++, n--;
  cout << N - cnt << "\n";
}