foo.cc: In function 'int merge(int, int)':
foo.cc:27:1: warning: control reaches end of non-void function [-Wreturn-type]
   27 | }
      | ^
foo.cc: In function 'int main()':
foo.cc:53:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   53 |  scanf("%d",&n);
      |  ~~~~~^~~~~~~~~
foo.cc:54:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   54 |  scanf("%s",str+1);
      |  ~~~~~^~~~~~~~~~~~

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