answer.code: In function ‘int32_t main()’:
answer.code:68:62: error: no matching function for call to ‘max(int&, int64_t)’
   68 |                                         while (x > 0) d = max(d, x % 10), x /= 10;
      |                                                           ~~~^~~~~~~~~~~
In file included from /usr/include/c++/11/bits/specfun.h:45,
                 from /usr/include/c++/11/cmath:1935,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41,
                 from answer.code:3:
/usr/include/c++/11/bits/stl_algobase.h:254:5: note: candidate: ‘template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)’
  254 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/11/bits/stl_algobase.h:254:5: note:   template argument deduction/substitution failed:
answer.code:68:62: note:   deduced conflicting types for parameter ‘const _Tp’ (‘int’ and ‘int64_t’ {aka ‘long int’})
   68 |                                         while (x > 0) d = max(d, x % 10), x /= 10;
      |                                                           ~~~^~~~~~~~~~~
In file included from /usr/include/c++/11/bits/specfun.h:45,
                 from /usr/include/c++/11/cmath:1935,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41,
                 from answer.code:3:
/usr/include/c++/11/bits/stl_algobase.h:300:5: note: candidate: ‘template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)’
  300 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/11/bits/stl_algobase.h:300:5: note:   template argument deduction/substitution failed:
answer.code:68:62: note:   deduced conflicting types for parameter ‘const _Tp’ (‘int’ and ‘int64_t’ {aka ‘long int’})
   68 |                                         while (x > 0) d = max(d, x % 10), x /= 10;
      |                                                           ~~~^~~~~~~~~~~
In file included from /usr/include/c++/11/string:52,
                 from /usr/include/c++/11/bits/locale_classes.h:40,
                 from /usr/include/c++/11/bits/ios_base.h:41,
                 from /usr/include/c++/11/ios:42,
                 from /usr/include/c++/11/istream:38,
                 from /usr/include/c++/11/sstream:38,
                 from /usr/include/c++/11/complex:45,
                 from /usr/include/c++/11/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:54,
                 from answer.code:3:
/usr/include/c++/11/bits/stl_algo.h:3461:5: note: candidate: ‘template<class _Tp> constexpr _Tp std::max(std::initializer_list<_Tp>)’
 3461 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/11/bits/stl_algo.h:3461:5: note:   template argument deduction/substitution failed:
answer.code:68:62: note:   mismatched types ‘std::initializer_list<_Tp>’ and ‘int’
   68 |                                         while (x > 0) d = max(d, x % 10), x /= 10;
      |                                                           ~~~^~~~~~~~~~~
In file included from /usr/include/c++/11/string:52,
                 from /usr/include/c++/11/bits/locale_classes.h:40,
                 from /usr/include/c++/11/bits/ios_base.h:41,
                 from /usr/include/c++/11/ios:42,
                 from /usr/include/c++/11/istream:38,
                 from /usr/include/c++/11/sstream:38,
                 from /usr/include/c++/11/complex:45,
                 from /usr/include/c++/11/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:54,
                 from answer.code:3:
/usr/include/c++/11/bits/stl_algo.h:3467:5: note: candidate: ‘template<class _Tp, class _Compare> constexpr _Tp std::max(std::initializer_list<_Tp>, _Compare)’
 3467 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/11/bits/stl_algo.h:3467:5: note:   template argument deduction/substitution failed:
answer.code:68:62: note:   mismatched types ‘std::initializer_list<_Tp>’ and ‘int’
   68 |                                         while (x > 0) d = max(d, x % 10), x /= 10;
      |                                                           ~~~^~~~~~~~~~~