foo.c:6:5: error: unknown type name 'Node'
    6 |     Node* next;
      |     ^~~~
foo.c:9:12: error: unknown type name 'Node'
    9 | int Search(Node* &head, int x)
      |            ^~~~
foo.c:24:13: error: unknown type name 'Node'
   24 | void Insert(Node* head, int x)
      |             ^~~~
foo.c: In function 'main':
foo.c:48:5: error: unknown type name 'Node'; use 'struct' keyword to refer to the type
   48 |     Node* head = NULL;
      |     ^~~~
      |     struct 
foo.c:52:9: warning: implicit declaration of function 'Insert' [-Wimplicit-function-declaration]
   52 |         Insert(head, k);
      |         ^~~~~~
foo.c:55:12: warning: implicit declaration of function 'Search' [-Wimplicit-function-declaration]
   55 |     int h= Search(head, x);
      |            ^~~~~~

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