#include <iostream>
#include <vector>

using namespace std;

int main()
{
	int N, maxi;
	vector<int> a;
	
	cin >> N;
	for (int i = 0, x, max = 0; i < N; ++i) {
		cin >> x;
		a.push_back(x);
		
		if (max < x) max = x, maxi = i;
	}
	
	int res = N;
	if (maxi == N-1) {
		for (int i = N-1; i >= 0; --i) {
			if (a[i] == i) --res;
			else break;
		}
	}
	
	cout << res << endl;
	
	return 0;
}