answer.code:6:7: error: size of array ‘a’ is not an integral constant-expression
    6 | int a[n], b[n];
      |       ^
answer.code:6:13: error: size of array ‘b’ is not an integral constant-expression
    6 | int a[n], b[n];
      |             ^
In file included from /usr/include/c++/13/algorithm:61,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:51,
                 from answer.code:1:
/usr/include/c++/13/bits/stl_algo.h: In instantiation of ‘void std::random_shuffle(_RAIter, _RAIter, _Generator&&) [with _RAIter = int*; _Generator = mersenne_twister_engine<long unsigned int, 32, 624, 397, 31, 2567483615, 11, 4294967295, 7, 2636928640, 15, 4022730752, 18, 1812433253>&]’:
answer.code:46:23:   required from here
/usr/include/c++/13/bits/stl_algo.h:4636:55: error: no match for call to ‘(std::mersenne_twister_engine<long unsigned int, 32, 624, 397, 31, 2567483615, 11, 4294967295, 7, 2636928640, 15, 4022730752, 18, 1812433253>) (long int)’
 4636 |           _RandomAccessIterator __j = __first + __rand((__i - __first) + 1);
      |                                                 ~~~~~~^~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/13/random:51,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:179:
/usr/include/c++/13/bits/random.h:587:7: note: candidate: ‘std::mersenne_twister_engine<_UIntType, __w, __n, __m, __r, __a, __u, __d, __s, __b, __t, __c, __l, __f>::result_type std::mersenne_twister_engine<_UIntType, __w, __n, __m, __r, __a, __u, __d, __s, __b, __t, __c, __l, __f>::operator()() [with _UIntType = long unsigned int; long unsigned int __w = 32; long unsigned int __n = 624; long unsigned int __m = 397; long unsigned int __r = 31; _UIntType __a = 2567483615; long unsigned int __u = 11; _UIntType __d = 4294967295; long unsigned int __s = 7; _UIntType __b = 2636928640; long unsigned int __t = 15; _UIntType __c = 4022730752; long unsigned int __l = 18; _UIntType __f = 1812433253; result_type = long unsigned int]’
  587 |       operator()();
      |       ^~~~~~~~
/usr/include/c++/13/bits/random.h:587:7: note:   candidate expects 0 arguments, 1 provided