#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, srt, end) for (long long i = (srt); i < (long long)(end); i++)
// Ref: https://qiita.com/ysuzuki19/items/d89057d65284ba1a16ac
#define dump(var)  do{std::cerr << #var << " : ";view(var);}while(0)
template<typename T> void view(T e){std::cerr << e << "\n";}
template<typename T> void view(const std::vector<T>& v){for(const auto& e : v){ std::cerr << e << " "; } std::cerr << "\n";}
template<typename T> void view(const std::vector<std::vector<T> >& vv){ std::cerr << "\n"; for(const auto& v : vv){ view(v); } }
template<typename T> void dump_cout(const T& v) { for(long long i = 0; i < v.size(); i++) std::cout << v[i] << (i == v.size()-1 ? "\n" : " "); }

void solve() {
    ll n;
    cin >> n;
    vector<ll> p(n);
    rep(i, 0, n) cin >> p[i];
    if(n == 1) {
        cout << 0 << endl;
        return;
    }
    vector<ll> idx(n);
    iota(idx.begin(), idx.end(), 0);
    sort(idx.begin(), idx.end(), [&](auto l, auto r) {
        return p[l] > p[r];
    } );
    ll ans = 0, rem = n * (n+1) / 2;
    for(auto e : idx) {
        rem -= e+1;
        ans = max(ans, rem - (e+1));
    }
    cout << ans << endl;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    solve();
    return 0;
}