#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
int INF = 1e9;
int MOD = 1000000007;
main(){
    int N,A[100000];
    cin >> N;
    int ans = N;
    for(int i = 0;i < N;i++)cin >> A[i];
    for(int i = N-1;i >= 0;i--){
        if(A[i] == ans)ans--;
    }
    cout << ans << endl;
}