#include <bits/stdc++.h>
using namespace std;

#define rep(i,n) for (int i=0;i<(n);i++)
#define rep2(i,a,b) for (int i=(a);i<(b);i++)
#define rrep(i,n) for (int i=(n)-1;i>=0;i--)
#define rrep2(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define all(a) (a).begin(),(a).end()

typedef long long ll;
typedef pair<int, int> P;

const int MAX_N = 100000;

vector<int> input(){
    string line;
    getline(cin, line);
    stringstream ss(line);

    vector<int> in;
    int x;
    while (ss >> x) {
        in.emplace_back(x);
    }

    return in;
}

signed main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

    vector<int> in = input();
    assert(in.size() == 1);
    int N = in[0];
    assert(1 <= N && N <= MAX_N);

    vector<int> a = input();
    assert(a.size() == N);
    set<int> s;
    rep(i, N) {
        assert(1 <= a[i] && a[i] <= N);
        assert(s.count(a[i]) == 0);
        s.insert(a[i]);
    }


    int buttom = N;
    rrep(i, N) {
        if (a[i] == buttom) buttom--;
    }

    cout << buttom << endl;

}