#include<iostream>
#include<vector>
#include<algorithm>

using namespace std;

int main(){
	int n;
	cin >> n;
	vector<int> a(n);
	for(auto &i : a){
		cin >> i;
	}
	int t = n;
	for(int i = n - 1; i >= 0; i--){
		if(a[i] == t)
			t--;
		
	}
	cout << t << endl;
	return 0;
}