#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<bitset>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<deque>
#include<list>
#include<iomanip>
#include<cmath>
#include<cstring>
#include<functional>
using namespace std;

#define repr(i, a, b) for (int i = (int)(a); i < (int)(b); i++)
#define rep(i, n) repr(i, 0, n)
#define INF 2e9
#define MOD 1000000007
//#define MOD 998244353
#define LINF (long long)4e18
#define jck 3.141592

using ll = long long;
using Pi = pair<int,int>;
using Pl = pair<ll,ll>;

int main(){
    int N; cin >> N;
    vector<int> a(N);
    rep(i,N) cin >> a[i],a[i]--;
    vector<int> s(N);
    rep(i,N){
        s[a[i]] = i;
    }
    int now = INF;
    int ans = 0;
    for(int i = N-1; i >= 0; i--){
        if(s[i] > now){
            ans = i+1;
            break;
        }
        now = s[i];
    }
    cout << ans << endl;

}