/in/foo.cc: In function 'int main()':
/in/foo.cc:47:14: error: no matching function for call to 'SeqList::MergeArr()'
   L.MergeArr();
              ^
/in/foo.cc:15:8: note: candidate: void SeqList::MergeArr(int*, int*, int, int)
   void MergeArr(int a[], int b[], int la, int lb);
        ^~~~~~~~
/in/foo.cc:15:8: note:   candidate expects 4 arguments, 0 provided