/in/foo.cc: In function 'int main()':
/in/foo.cc:9:5: error: 'Record' was not declared in this scope
     Record* A = new Record[na];
     ^~~~~~
/in/foo.cc:9:13: error: 'A' was not declared in this scope
     Record* A = new Record[na];
             ^
/in/foo.cc:9:21: error: 'Record' does not name a type
     Record* A = new Record[na];
                     ^~~~~~
/in/foo.cc:15:13: error: 'B' was not declared in this scope
     Record* B = new Record[nb];
             ^
/in/foo.cc:15:21: error: 'Record' does not name a type
     Record* B = new Record[nb];
                     ^~~~~~
/in/foo.cc:21:20: error: 'MergeSort' was not declared in this scope
     MergeSort(A, na);   // 对数组A进行归并排序
                    ^
/in/foo.cc:46:14: error: type '<type error>' argument given to 'delete', expected pointer
     delete[] A;
              ^
/in/foo.cc:47:14: error: type '<type error>' argument given to 'delete', expected pointer
     delete[] B;
              ^