answer.code: In function ‘i64 split(i64, i64)’:
answer.code:86:1: warning: no return statement in function returning non-void [-Wreturn-type]
   86 | }
      | ^
answer.code: In function ‘void merge(i64, i64)’:
answer.code:92:20: error: expected primary-expression before ‘)’ token
   92 |                 if()
      |                    ^
answer.code:93:9: error: expected primary-expression before ‘}’ token
   93 |         }
      |         ^
answer.code: In function ‘int main()’:
answer.code:105:11: warning: ISO C++17 does not allow ‘register’ storage class specifier [-Wregister]
  105 |         F(i,1,n)fa[i]=n+1,siz[i]=1;
      |           ^
answer.code:27:34: note: in definition of macro ‘F’
   27 | #define F(i,j,n)for(register int i=j;i<=n;i++)
      |                                  ^