foo.cc: In function 'int main()':
foo.cc:11:23: warning: unused variable 'q' [-Wunused-variable]
     pNode head, p, s, q;
                       ^
foo.cc:18:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
foo.cc:21:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &x);
         ~~~~~^~~~~~~~~~

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