#include<bits/stdc++.h>
using namespace std;
int a[100000];
int main(){
  int n;
  cin>>n;
  int now;
  int maxc=0;
  for(int i=0;i<n;i++){
    cin>>a[i];
  }
  now = n;
  for(int i=n-1;i>=0;i--){
    if(a[i] == now){
      now--;
      maxc++;
    }
  }

  cout<<n-maxc<<endl;
}