foo.cc: In function 'int main()':
foo.cc:22:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   22 |     int n; scanf("%d",&n);
      |            ~~~~~^~~~~~~~~
foo.cc:24:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   24 |         int x; scanf("%d",&x);
      |                ~~~~~^~~~~~~~~
foo.cc:28:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   28 |         scanf("%d",&col[i]);
      |         ~~~~~^~~~~~~~~~~~~~

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