Language: C++

#include<bits/stdc++.h>
using namespace std;
#define s second
#define f first
int dx[]={1,0,1,-1};
int dy[]={0,1,1,1};
int main(){
  int n;
  while(cin>>n,n){
    string s[n];
    for(int i=0;i<n;i++)cin>>s[i];
    pair<pair<int,int>,pair<int,int> > a[n][n];
    for(int i=0;i<n;i++)
      for(int j=0;j<n;j++)
    a[i][j].f.f=a[i][j].f.s=a[i][j].s.f=a[i][j].s.s=s[i][j]-'0';    
    for(int i=0;i<n;i++)
      for(int j=0;j<n;j++)
    for(int k=0;k<4;k++){
      int x=j+dx[k],y=i+dy[k];
      if(x>=0&&y>=0&&y<n&&x<n){
        if(k==0&&a[y][x])a[y][x].f.f+=a[i][j].f.f;
        if(k==1&&a[y][x])a[y][x].f.s+=a[i][j].f.s;
        if(k==2&&a[y][x])a[y][x].s.f+=a[i][j].s.f;
        if(k==3&&a[y][x])a[y][x].s.s+=a[i][j].s.s;
      }
    }
    int res=0;
    for(int i=0;i<n;i++)
      for(int j=0;j<n;j++){
    res=max(res,a[i][j].f.f);
    res=max(res,a[i][j].f.s);
    res=max(res,a[i][j].s.f);
    res=max(res,a[i][j].s.s);
      }
    cout<<res<<endl;
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:21:16: error: no match for 'operator&&' (operand types are 'bool' and 'std::pair<std::pair<int, int>, std::pair<int, int> >')
   21 |         if(k==0&&a[y][x])a[y][x].f.f+=a[i][j].f.f;
      |            ~~~~^~~~~~~~~
      |             |          |
      |             bool       std::pair<std::pair<int, int>, std::pair<int, int> >
a.cc:21:16: note: candidate: 'operator&&(bool, bool)' (built-in)
   21 |         if(k==0&&a[y][x])a[y][x].f.f+=a[i][j].f.f;
      |            ~~~~^~~~~~~~~
a.cc:21:16: note:   no known conversion for argument 2 from 'std::pair<std::pair<int, int>, std::pair<int, int> >' to 'bool'
In file included from /usr/include/c++/14/valarray:605,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166,
                 from a.cc:1:
/usr/include/c++/14/bits/valarray_after.h:415:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__logical_and, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__logical_and, typename _Dom1::value_type>::result_type> std::operator&&(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  415 |     _DEFINE_EXPR_BINARY_OPERATOR(&&, struct std::__logical_and)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:415:5: note:   template argument deduction/substitution failed:
a.cc:21:24: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'bool'
   21 |         if(k==0&&a[y][x])a[y][x].f.f+=a[i][j].f.f;
      |                        ^
/usr/include/c++/14/bits/valarray_after.h:415:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__logical_and, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__logical_and, typename _Dom1::value_type>::result_type> std::operator&&(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  415 |     _DEFINE_EXPR_BINARY_OPERATOR(&&, struct std::__logical_and)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:415:5: note:   template argument deduction/substitution failed:
a.cc:21:24: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'bool'
   21 |         if(k==0&&a[y][x])a[y][x].f.f+=a[i][j].f.f;
      |                        ^
/usr/include/c++/14/bits/valarray_after.h:415:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__logical_and, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__logical_and, typename _Dom1::value_type>::result_type> std::operator&&(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  415 |     _DEFINE_EXPR_BINARY_OPERATOR(&&, struct std::__logical_and)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:415:5: note:   template argument deduction/substitution failed:
a.cc:21:24: note:   'std::pair<std::pair<int, int>, std::pair<int, int> >' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   21 |         if(k==0&&a[y][x])a[y][x].f.f+=a[i][j].f.f;
      |                        ^
/usr/include/c++/14/bits/valarray_after.h:415:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__logical_and, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__logical_and, typename _Dom1::value_type>::result_type> std::operator&&(const _Expr<_Dom1, typename _Dom1::value_type>&, const valarray<typename _Dom::value_type>&)'
  415 |     _DEFINE_EXPR_BINARY_OPERATOR(&&, struct std::__logical_and)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:415:5: note:   template argument deduction/substitution failed:
a.cc:21:24: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'bool'
   21 |         if(k==0&&a[y][x])a[y][x].f.f+=a[i][j].f.f;
      |                        ^
/usr/include/c++/14/bits/valarray_after.h:415:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__logical_and, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__logical_and, typename _Dom1::value_type>::result_type> std::operator&&(const valarray<typename _Dom::value_type>&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  415 |     _DEFINE_EXPR_BINARY_OPERATOR(&&, struct std::__logical_and)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:415:5: note:   template argument deduction/substitution failed:
a.cc:21:24: note:   'std::pair<std::pair<int, int>, std::pair<int, int> >' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   21 |         if(k==0&&a[y][x])a[y][x].f.f+=a[i][j].f.f;
      |                        ^
/usr/include/c++/14/valarray:1206:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__logical_and, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__logical_and, _Tp>::result_type> std::operator&&(const valarray<_Tp>&, const valarray<_Tp>&)'
 1206 | _DEFINE_BINARY_OPERATOR(&&, __logical_and)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1206:1: note:   template argument deduction/substitution failed:
a.cc:21:24: note:   mismatched types 'const std::valarray<_Tp>' and 'bool'
   21 |         if(k==0&&a[y][x])a[y][x].f.f+=a[i][j].f.f;
      |                        ^
/usr/include/c++/14/valarray:1206:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__logical_and, std::_ValArray, std::_Constant, _Tp, _Tp>, typename std::__fun<std::__logical_and, _Tp>::result_type> std::operator&&(const valarray<_Tp>&, const typename valarray<_Tp>::value_type&)'
 1206 | _DEFINE_BINARY_OPERATOR(&&, __logical_and)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1206:1: note:   template argument deduction/substitution failed:
a.cc:21:24: note:   mismatched types 'const std::valarray<_Tp>' and 'bool'
   21 |         if(k==0&&a[y][x])a[y][x].f.f+=a[i][j].f.f;
      |                        ^
/usr/include/c++/14/valarray:1206:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__logical_and, std::_Constant, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__logical_and, _Tp>::result_type> std::operator&&(const typename valarray<_Tp>::value_type&, const valarray<_Tp>&)'
 1206 | _DEFINE_BINARY_OPERATOR(&&, __logical_and)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1206:1: note:   template argument deduction/substitution failed:
a.cc:21:24: note:   'std::pair<std::pair<int, int>, std::pair<int, int> >' is not derived from 'const std::valarray<_Tp>'
   21 |         if(k==0&&a[y][x])a[y][x].f.f+=a[i][j].f.f;
      |                        ^
a.cc:22:16: error: no match for 'operator&&' (operand types are 'bool' and 'std::pair<std::pair<int, int>, std::pair<int, int> >')
   22 |         if(k==1&&a[y][x])a[y][x].f.s+=a[i][j].f.s;
      |            ~~~~^~~~~~~~~
      |             |          |
      |             bool       std::pair<std::pair<int, int>, std::pair<int, int> >
a.cc:22:16: note: candidate: 'operator&&(bool, bool)' (built-in)
   22 |         if(k==1&&a[y][x])a[y][x].f.s+=a[i][j].f.s;
      |            ~~~~^~~~~~~~~
a.cc:22:16: note:   no known conversion for argument 2 from 'std::pair<std::pair<int, int>, std::pair<int, int> >' to 'bool'
/usr/include/c++/14/bits/valarray_after.h:415:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__logical_and, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__logical_and, typename _Dom1::value_type>::result_type> std::operator&&(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  415 |     _DEFINE_EXPR_BINARY_OPERATOR(&&, struct std::__logical_and)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:415:5: note:   template argument deduction/substitution failed:
a.cc:22:24: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'bool'
   22 |         if(k==1&&a[y][x])a[y][x].f.s+=a[i][j].f.s;
      |                        ^
/usr/include/c++/14/bits/valarray_after.h:415:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__logical_and, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__logical_and, typename _Dom1::value_type>::result_type> std::operator&&(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  415 |     _DEFINE_EXPR_BINARY_OPERATOR(&&, struct std::__logical_and)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:415:5: note:   template argument deduction/substitution failed:
a.cc:22:24: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'bool'
   22 |         if(k==1&&a[y][x])a[y][x].f.s+=a[i][j].f.s;
      |                        ^
/usr/include/c++/14/bits/valarray_after.h:415:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__logical_and, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__logical_and, typename _Dom1::value_type>::result_type> std::operator&&(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  415 |     _DEFINE_EXPR_BINARY_OPERATOR(&&, struct std::__logical_and)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:415:5: note:   template argument deduction/substitution failed:
a.cc:22:24: note:   'std::pair<std::pair<int, int>, std::pair<int, int> >' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   22 |         if(k==1&&a[y][x])a[y][x].f.s+=a[i][j].f.s;
      |                        ^
/usr/include/c++/14/bits/valarray_after.h:415:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__logical_and, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std