foo.cc: In function 'int main()':
foo.cc:70:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld%lld%lld", &n, &m, &s);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:76:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld%lld%lld", &u, &v, &w);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

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