#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <functional>
#include <bitset>
#include <cstddef>
#include <type_traits>
#include <vector>

using namespace std;
using lint = long long int;
long long int INF = 1001001001001001LL;
int inf = 1000000007;
long long int MOD = 1000000007LL;
double PI = 3.1415926535897932;

template<typename T1,typename T2>inline void chmin(T1 &a,const T2 &b){if(a>b) a=b;}
template<typename T1,typename T2>inline void chmax(T1 &a,const T2 &b){if(a<b) a=b;}

#define ALL(a) a.begin(),a.end()
#define RALL(a) a.rbegin(),a.rend()
#define rep(i, n) for(int i=0;i<(int)(n);i++)


int main() {
 
  int n; cin >> n;
  vector<int> p(n);
  vector<int> ids(n + 1);
  rep (i, n) {
    cin >> p[i];
    ids[p[i]] = i + 1;
  }

  lint ans = 0;
  lint add = 0;
  for (int i = 2; i <= n; i++) {
    // i は負け
    // i - 1 以下はかち
    // i + 1 以上は同点
    add += ids[i - 1];
    chmax(ans, add - ids[i]);
  }
  cout << ans << endl;
  return 0;
}