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

#define REP(i,n) for(int i=0;i<n;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define INF INT_MAX/3
#define LINF LLONG_MAX/3
#define MP make_pair
#define PB push_back
#define EB emplace_back
#define ALL(v) (v).begin(),(v).end()
#define debug(x) cout<<#x<<":"<<x<<endl
#define debug2(x,y) cout<<#x<<","<<#y":"<<x<<","<<y<<endl
template<typename T>
ostream& operator<<(ostream& os,const vector<T>& vec){
    os << "[";
    for(const auto& v : vec){
        os << v << ",";
    }
    os << "]";
    return os;
}

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;

int main(){
    int N; cin >> N;
    vector<int> a(N);
    rep(i,N) cin>>a[i];

    int last = N;
    int count = 0;
    for(int i=N-1;i>=0;i--){
        if(a[i]==last){
            count++;
            last--;
        }
    }
    cout << N - count << endl;
}