foo.cc: In function 'int main()':
foo.cc:26:9: warning: unused variable 'last' [-Wunused-variable]
   26 |     int last = 0;
      |         ^~~~
foo.cc:25:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   25 |     scanf("%d", &N);
      |     ~~~~~^~~~~~~~~~
foo.cc:28:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   28 |         scanf("%d", &stones[i].left);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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