#include<bits/stdc++.h>
using namespace std;
using Int = long long;
//INSERT ABOVE HERE
signed main(){
  Int n;
  cin>>n;
  vector<Int> a(n);
  for(Int i=0;i<n;i++) cin>>a[i];
  reverse(a.begin(),a.end());
  Int k=n;
  for(Int i=0;i<n;i++) if(a[i]==k) k--;
  cout<<k<<endl;
  return 0;
}