#include <bits/stdc++.h>

using namespace std;

#define _GLIBCXX_DEBUG
#define dump(c) cerr << "> " << #c << " = " << (c) << endl
#define all(c) ((c).begin()), ((c).end())
#define rep(i, n) for(int i=0;i<(int)n;i++)
#define FOR(i, s, e) for(int (i)=(int)(s);(i)<(int)(e);++(i))
#define inf 0x3f3f3f3f
#define infl 0x3f3f3f3f3f3f3f3fLL

typedef long long ll;
typedef unsigned long long ull;

int main() {
    int N;
    cin >> N;
    vector<int> a(N);
    for (int i = 0; i < N; ++i) cin >> a[i];
    int count = 0;
    int d = N+1;
    for (int j = N-1; j >= 0; --j) {
        if (a[j] == d - 1) {
            count++;
            d = d - 1;
        }
    }

    cout << N - count << endl;

    return 0;
}