answer.code: In function ‘int main()’:
answer.code:51:68: error: ‘mod’ was not declared in this scope; did you mean ‘mid’?
   51 |             if((hash1.gethash(1,mid-2*k)+hash1.gethash(2*k+1,mid))%mod==hash1.gethash(k+1,mid-k)*2%mod
      |                                                                    ^~~
      |                                                                    mid
answer.code: In function ‘int gtnum(char)’:
answer.code:26:1: warning: control reaches end of non-void function [-Wreturn-type]
   26 | }
      | ^