Language: C++

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

int main(){
  
  int n,m;
  cin >>n >>m;
  
  for(int i=0; i<m; i++){
    int a,b;
    long ans;
    vector<int>h(6);
    h[1],h[2],h[3],h[4],h[5],h[6] = 0;
    vector<int>l(6);
    l[1],l[2],l[3],l[4],l[5],l[6] = 0;
    
    cin >>a >>b;
    reverce(a.begin(),a.end());
    reverce(b.begin().b.end());
    
    h[1] = a-a/10*10;
    h[2] = a/10-a/100*10;
    h[3] = a/100-a/1000*10;
    h[4] = a/1000-a/10000*10;
    h[5] = a/10000-a/100000*10;
    h[6] = a/100000;
    
    l[1] = b-b/10*10;
    l[2] = b/10-b/100*10;
    l[3] = b/100-b/1000*10;
    l[4] = b/1000-b/10000*10;
    l[5] = b/10000-b/100000*10;
    l[6] = b/100000;
    
    reverce(h.begin(),h.end());
    reverce(l.begin().l.end());
    
    ans = h*1000000+l;
    cout <<ans <<endl;
  }
  
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:13:8: warning: ignoring return value of 'std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = int; _Alloc = std::allocator<int>; reference = int&; size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result]
   13 |     h[1],h[2],h[3],h[4],h[5],h[6] = 0;
      |        ^
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_vector.h:1128:7: note: declared here
 1128 |       operator[](size_type __n) _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~
a.cc:13:13: warning: ignoring return value of 'std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = int; _Alloc = std::allocator<int>; reference = int&; size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result]
   13 |     h[1],h[2],h[3],h[4],h[5],h[6] = 0;
      |             ^
/usr/include/c++/14/bits/stl_vector.h:1128:7: note: declared here
 1128 |       operator[](size_type __n) _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~
a.cc:13:18: warning: ignoring return value of 'std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = int; _Alloc = std::allocator<int>; reference = int&; size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result]
   13 |     h[1],h[2],h[3],h[4],h[5],h[6] = 0;
      |                  ^
/usr/include/c++/14/bits/stl_vector.h:1128:7: note: declared here
 1128 |       operator[](size_type __n) _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~
a.cc:13:23: warning: ignoring return value of 'std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = int; _Alloc = std::allocator<int>; reference = int&; size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result]
   13 |     h[1],h[2],h[3],h[4],h[5],h[6] = 0;
      |                       ^
/usr/include/c++/14/bits/stl_vector.h:1128:7: note: declared here
 1128 |       operator[](size_type __n) _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~
a.cc:13:28: warning: ignoring return value of 'std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = int; _Alloc = std::allocator<int>; reference = int&; size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result]
   13 |     h[1],h[2],h[3],h[4],h[5],h[6] = 0;
      |                            ^
/usr/include/c++/14/bits/stl_vector.h:1128:7: note: declared here
 1128 |       operator[](size_type __n) _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~
a.cc:15:8: warning: ignoring return value of 'std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = int; _Alloc = std::allocator<int>; reference = int&; size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result]
   15 |     l[1],l[2],l[3],l[4],l[5],l[6] = 0;
      |        ^
/usr/include/c++/14/bits/stl_vector.h:1128:7: note: declared here
 1128 |       operator[](size_type __n) _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~
a.cc:15:13: warning: ignoring return value of 'std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = int; _Alloc = std::allocator<int>; reference = int&; size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result]
   15 |     l[1],l[2],l[3],l[4],l[5],l[6] = 0;
      |             ^
/usr/include/c++/14/bits/stl_vector.h:1128:7: note: declared here
 1128 |       operator[](size_type __n) _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~
a.cc:15:18: warning: ignoring return value of 'std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = int; _Alloc = std::allocator<int>; reference = int&; size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result]
   15 |     l[1],l[2],l[3],l[4],l[5],l[6] = 0;
      |                  ^
/usr/include/c++/14/bits/stl_vector.h:1128:7: note: declared here
 1128 |       operator[](size_type __n) _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~
a.cc:15:23: warning: ignoring return value of 'std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = int; _Alloc = std::allocator<int>; reference = int&; size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result]
   15 |     l[1],l[2],l[3],l[4],l[5],l[6] = 0;
      |                       ^
/usr/include/c++/14/bits/stl_vector.h:1128:7: note: declared here
 1128 |       operator[](size_type __n) _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~
a.cc:15:28: warning: ignoring return value of 'std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = int; _Alloc = std::allocator<int>; reference = int&; size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result]
   15 |     l[1],l[2],l[3],l[4],l[5],l[6] = 0;
      |                            ^
/usr/include/c++/14/bits/stl_vector.h:1128:7: note: declared here
 1128 |       operator[](size_type __n) _GLIBCXX_NOEXCEPT
      |       ^~~~~~~~
a.cc:18:15: error: request for member 'begin' in 'a', which is of non-class type 'int'
   18 |     reverce(a.begin(),a.end());
      |               ^~~~~
a.cc:18:25: error: request for member 'end' in 'a', which is of non-class type 'int'
   18 |     reverce(a.begin(),a.end());
      |                         ^~~
a.cc:18:5: error: 'reverce' was not declared in this scope
   18 |     reverce(a.begin(),a.end());
      |     ^~~~~~~
a.cc:19:15: error: request for member 'begin' in 'b', which is of non-class type 'int'
   19 |     reverce(b.begin().b.end());
      |               ^~~~~
a.cc:36:23: error: 'std::vector<int>::iterator' has no member named 'l'
   36 |     reverce(l.begin().l.end());
      |                       ^
a.cc:38:12: error: no match for 'operator*' (operand types are 'std::vector<int>' and 'int')
   38 |     ans = h*1000000+l;
      |           ~^~~~~~~~
      |           | |
      |           | int
      |           std::vector<int>
In file included from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/complex:400:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator*(const complex<_Tp>&, const complex<_Tp>&)'
  400 |     operator*(const complex<_Tp>& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:400:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   'std::vector<int>' is not derived from 'const std::complex<_Tp>'
   38 |     ans = h*1000000+l;
      |             ^~~~~~~
/usr/include/c++/14/complex:409:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator*(const complex<_Tp>&, const _Tp&)'
  409 |     operator*(const complex<_Tp>& __x, const _Tp& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:409:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   'std::vector<int>' is not derived from 'const std::complex<_Tp>'
   38 |     ans = h*1000000+l;
      |             ^~~~~~~
/usr/include/c++/14/complex:418:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator*(const _Tp&, const complex<_Tp>&)'
  418 |     operator*(const _Tp& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:418:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   mismatched types 'const std::complex<_Tp>' and 'int'
   38 |     ans = h*1000000+l;
      |             ^~~~~~~
In file included from /usr/include/c++/14/valarray:605,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166:
/usr/include/c++/14/bits/valarray_after.h:407:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__multiplies, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__multiplies, typename _Dom1::value_type>::result_type> std::operator*(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  407 |     _DEFINE_EXPR_BINARY_OPERATOR(*, struct std::__multiplies)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   'std::vector<int>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   38 |     ans = h*1000000+l;
      |             ^~~~~~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__multiplies, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__multiplies, typename _Dom1::value_type>::result_type> std::operator*(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  407 |     _DEFINE_EXPR_BINARY_OPERATOR(*, struct std::__multiplies)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   'std::vector<int>' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   38 |     ans = h*1000000+l;
      |             ^~~~~~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__multiplies, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__multiplies, typename _Dom1::value_type>::result_type> std::operator*(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  407 |     _DEFINE_EXPR_BINARY_OPERATOR(*, struct std::__multiplies)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:407:5: note:   template argument deduction/substitution failed:
a.cc:38:13: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   38 |     ans = h*1000000+l;
      |             ^~~~~~~
/usr/include/c++/14/b