answer.code: In function ‘long long int check(vi)’:
answer.code:354:21: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘long long int’ [-Wformat=]
  354 |     rrg(n)printf("%2d ",i);gr puts("");
      |                   ~~^   ~
      |                     |   |
      |                     int long long int
      |                   %2lld
answer.code:355:21: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type’ {aka ‘long long int’} [-Wformat=]
  355 |     rrg(n)printf("%2d ",a[i]);gr puts("");
      |                   ~~^
      |                     |
      |                     int
      |                   %2lld
answer.code:356:21: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘long long int’ [-Wformat=]
  356 |     rrg(n)printf("%2d ",i^a[i]);gr puts("");
      |                   ~~^
      |                     |
      |                     int
      |                   %2lld
answer.code: In function ‘v3 build2n(long long int)’:
answer.code:370:1: warning: no return statement in function returning non-void [-Wreturn-type]
  370 | }
      | ^
answer.code: In function ‘v3 place(long long int, long long int)’:
answer.code:374:1: warning: no return statement in function returning non-void [-Wreturn-type]
  374 | }
      | ^
answer.code: In function ‘v3 build(long long int)’:
answer.code:383:16: error: ‘half’ was not declared in this scope
  383 |         return half(build2n(n));
      |                ^~~~
answer.code:385:8: error: redeclaration of ‘vi p’
  385 |     vi p,q,r,P,Q,R;
      |        ^
answer.code:379:8: note: ‘vi p’ previously declared here
  379 |     vi p,q,r;
      |        ^
answer.code:385:10: error: redeclaration of ‘vi q’
  385 |     vi p,q,r,P,Q,R;
      |          ^
answer.code:379:10: note: ‘vi q’ previously declared here
  379 |     vi p,q,r;
      |          ^
answer.code:385:12: error: redeclaration of ‘vi r’
  385 |     vi p,q,r,P,Q,R;
      |            ^
answer.code:379:12: note: ‘vi r’ previously declared here
  379 |     vi p,q,r;
      |            ^
answer.code:387:12: error: ‘half’ was not declared in this scope
  387 |     v3 tmp=half(build(z-n));
      |            ^~~~