#include <iostream>

int main()
{
    int N;
    std::cin >> N;
    int l = 0;
    int c = 0;
    for (int i = 0; i < N; ++i) {
        int A;
        std::cin >> A;
        if (l + 1 == A) {
            ++l;
            ++c;
        } else if (l <= A) {
            c = 1;
            l = A;
        }
    }
    std::cout << (N - c) << '\n';
}