#include <iostream>
using namespace std;
int N, a[100005];
int main()
{
  cin >> N;
  int i,n=N;
  for(i=0;i<N;i++) cin >> a[i];
  for(i=N-1;i>=0;i--) if(n==a[i]) n--;
  cout << n << endl; 
  return 0;
}