foo.cc: In function 'int main()':
foo.cc:10:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   10 | scanf("%d%d%d",&V,&M,&n);
      | ~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:13:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   13 | scanf("%d%d%d",&v[i],&m[i],&ka[i]);
      | ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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