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

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

    int n;
    cin >> n;

    vector<int> q(n);
    for (int i = 0; i < n; i++) {
        int p;
        cin >> p;
        p--;

        q[p] = i + 1;
    }

    ll r = 0, s = 0;
    for (int i = 0; i < n; i++) {
        if (i > 0) {
            r = max(r, s - q[i]);
        }
        s += q[i];
    }
    cout << r << endl;

    return 0;
}