/// @author Camillus
#include "bits/stdc++.h"
#define int long long
using namespace std;

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

    vector<int> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }

    vector<int> left(n), right(n);
    for (int i = 1; i < n; i++) {
        left[i] = left[i - 1] + max(0, a[i - 1] - a[i] + 1);
    }

    for (int i = n - 2; i >= 0; i--) {
        right[i] = right[i + 1] + max(0, a[i + 1] - a[i] + 1);
    }

    int ans = INT32_MAX;

    for (int i = 0; i < n; i++) {
        ans = min(ans, max(left[i], right[i]));
    }

    cout << ans << '\n';
    return 0;
}

answer.code: In function ‘int main()’:
answer.code:19:36: error: no matching function for call to ‘max(int, __gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type)’
   19 |         left[i] = left[i - 1] + max(0, a[i - 1] - a[i] + 1);
      |                                 ~~~^~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/13/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:51,
                 from answer.code:2:
/usr/include/c++/13/bits/stl_algobase.h:257:5: note: candidate: ‘template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)’
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/13/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
answer.code:19:36: note:   deduced conflicting types for parameter ‘const _Tp’ (‘int’ and ‘__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type’ {aka ‘long long int’})
   19 |         left[i] = left[i - 1] + max(0, a[i - 1] - a[i] + 1);
      |                                 ~~~^~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/bits/stl_algobase.h:303:5: note: candidate: ‘template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)’
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/13/bits/stl_algobase.h:303:5: note:   template argument deduction/substitution failed:
answer.code:19:36: note:   deduced conflicting types for parameter ‘const _Tp’ (‘int’ and ‘__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type’ {aka ‘long long int’})
   19 |         left[i] = left[i - 1] + max(0, a[i - 1] - a[i] + 1);
      |                                 ~~~^~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/13/algorithm:61:
/usr/include/c++/13/bits/stl_algo.h:5795:5: note: candidate: ‘template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)’
 5795 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/13/bits/stl_algo.h:5795:5: note:   template argument deduction/substitution failed:
answer.code:19:36: note:   mismatched types ‘std::initializer_list<_Tp>’ and ‘int’
   19 |         left[i] = left[i - 1] + max(0, a[i - 1] - a[i] + 1);
      |                                 ~~~^~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/bits/stl_algo.h:5805:5: note: candidate: ‘template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)’
 5805 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/13/bits/stl_algo.h:5805:5: note:   template argument deduction/substitution failed:
answer.code:19:36: note:   mismatched types ‘std::initializer_list<_Tp>’ and ‘int’
   19 |         left[i] = left[i - 1] + max(0, a[i - 1] - a[i] + 1);
      |                                 ~~~^~~~~~~~~~~~~~~~~~~~~~~~
answer.code:23:38: error: no matching function for call to ‘max(int, __gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type)’
   23 |         right[i] = right[i + 1] + max(0, a[i + 1] - a[i] + 1);
      |                                   ~~~^~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/bits/stl_algobase.h:257:5: note: candidate: ‘template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)’
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/13/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
answer.code:23:38: note:   deduced conflicting types for parameter ‘const _Tp’ (‘int’ and ‘__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type’ {aka ‘long long int’})
   23 |         right[i] = right[i + 1] + max(0, a[i + 1] - a[i] + 1);
      |                                   ~~~^~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/bits/stl_algobase.h:303:5: note: candidate: ‘template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)’
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/13/bits/stl_algobase.h:303:5: note:   template argument deduction/substitution failed:
answer.code:23:38: note:   deduced conflicting types for parameter ‘const _Tp’ (‘int’ and ‘__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type’ {aka ‘long long int’})
   23 |         right[i] = right[i + 1] + max(0, a[i + 1] - a[i] + 1);
      |                                   ~~~^~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/13/bits/stl_algo.h:5795:5: note: candidate: ‘template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)’
 5795 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/13/bits/stl_algo.h:5795:5: note:   template argument deduction/substitution failed:
answer.code:23:38: note:   mismatched types ‘std::initializer_list<_Tp>’ and ‘int’
   23 |         right[i] = right[i + 1] + ma...