answer.code: In function ‘int main()’:
answer.code:119:33: error: ‘assert’ was not declared in this scope
  119 |                                 assert(prt<=2*n*n);
      |                                 ^~~~~~
answer.code:6:1: note: ‘assert’ is defined in header ‘<cassert>’; did you forget to ‘#include <cassert>’?
    5 | #include<cstdlib>
  +++ |+#include <cassert>
    6 | 
answer.code:72:22: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   72 |                 scanf("%s", a[i]+1), p[i]=i;
      |                 ~~~~~^~~~~~~~~~~~~~