#include <algorithm>
#include <iostream>
#include <vector>

int main() {
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(nullptr);

  int N;
  std::cin >> N;

  std::vector<int> round(N + 1);
  for (int i = 0; i < N; ++i) {
    int p;
    std::cin >> p;
    round[p] = i + 1;
  }

  long long ans = 0, sum = static_cast<long long>(N) * (N + 1) / 2;

  for (int i = N; i > 0; --i) {
    sum -= round[i];
    ans = std::max(ans, sum - round[i]);
  }

  std::cout << ans << '\n';
}