answer.code: In function ‘void init()’:
answer.code:12:9: error: ‘ind’ was not declared in this scope; did you mean ‘int’?
   12 |         ind[i]=0;
      |         ^~~
      |         int
answer.code:13:9: error: ‘ind2’ was not declared in this scope
   13 |         ind2[i]=0;
      |         ^~~~
answer.code:15:9: error: ‘nex2’ was not declared in this scope; did you mean ‘nex1’?
   15 |         nex2[i].clear();
      |         ^~~~
      |         nex1
answer.code:16:9: error: ‘pre’ was not declared in this scope; did you mean ‘pread’?
   16 |         pre[i]=0;
      |         ^~~
      |         pread
answer.code:17:9: error: ‘book’ was not declared in this scope; did you mean ‘bool’?
   17 |         book[i]=0;
      |         ^~~~
      |         bool