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

using Int8 = int8_t;
using Int16 = int16_t;
using Int32 = int32_t;
using Int64 = int64_t;
using Int128 = __int128_t;

using Word8 = uint8_t;
using Word16 = uint16_t;
using Word32 = uint32_t;
using Word64 = uint64_t;
using Word128 = __uint128_t;

using Int = int_fast64_t;
using Word = uint_fast64_t;

using F32 = float;
using F64 = double;
using F80 = long double;

using VS = vector<string>;
using VVS = vector<vector<string>>;
using VB = vector<bool>;
using VVB = vector<vector<bool>>;
using VI = vector<Int>;
using VW = vector<Word>;
using VVI = vector<vector<Int>>;
using VVW = vector<vector<Word>>;
using PII = pair<Int,Int>;
using PWW = pair<Word,Word>;
using VPII = vector<pair<Int,Int>>;
using VPWW = vector<pair<Word,Word>>;

#define LOOP(n) for(Int _ipiewnsjiw=0; _ipiewnsjiw<(n); _ipiewnsjiw++)
#define REP(i,n) for(Int i=0, i##_len=(n); i<i##_len; ++i)
#define RANGE(i,a,b) for(Int i=(a), i##_len(b); i<=i##_len; ++i)
#define SZ(obj) ((Int)(obj).size())
#define UNIQUE(obj) (obj).erase(unique((obj).begin(),(obj).end()),(obj).end())
#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()

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

  int N; cin >> N;
  vector<int> A(N);
  int sum = 0;
  for (int i = 0; i < N; i++) {
    cin >> A[i];
    sum += A[i];
  }
  int t = (int)sqrt(sum + 0.1), ans = 0;
  for (int i = 0; i < N; i++) ans += max(0, A[i] - max(0, t - abs((t - 1) - i)));

  cout << ans << '\n';

  return 0;
}