#include <iostream>
#include <vector>
using namespace std;

int main() {
    int N;
    cin >> N;
    vector<int> A(N);
    for (int i = 0; i < N; i++)
    {
        cin >> A[i];
    }
    bool b = false;
    int cnt = 0;
    for (int i = N - 1; i >= 0; i--)
    {
        if (!b) {
            if (A[i] == N) {
                b = true;
                cnt++;
            }
        }
        else {
            if (A[i] == N - cnt) {
                cnt++;
            }
        }
    }
    cout << N - cnt << endl;
    getchar(); getchar();
    return 0;
}