#include <iostream>
#include <vector>

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