#include <iostream>

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