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

int main()
{
    ll n; cin >> n;
    vector<ll> v(n);
    for (ll i = 0; i < n; i++){
        cin >> v[i];
    }
    reverse(v.begin(), v.end());
    ll longest = 0, cur = 0, l = 0;
    for (ll i = 1; i < n; i++){
        cur++;
        if (v[i] < v[l]) continue;
        else {
            if (longest < cur) longest = cur;
            cur = 0; l = i;
            //cout << longest << " " << v[l] << " ";
        }
    }
    //if (longest < cur) longest = cur;
    if (longest < 2) cout << -1;
    else cout << longest;
    return 0;
}