#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
using namespace std;

#define ll long long
#define INF (1 << 30)
#define INFLL (1LL << 60)

int main() {
	int n;
	int a[100010] = {};
	cin >> n;
	for(int i = 0;i < n;i++){
		cin >> a[i];
	}
	int now = n,cou = 0;
	for(int i = n - 1;i >= 0;i--){
		if(a[i] == now) {
			cou++;
			now--;
		}
	}
	cout << n - cou << endl;
	return 0;
}