foo.cc: In function 'int main()':
foo.cc:85:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d", &u, &v, &cost);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:92:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &u);
         ~~~~~^~~~~~~~~~

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