foo.cc: In function 'int main()':
foo.cc:13:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d%d",&n,&m,&v,&e);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:14:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i=1;i<=n;i++) scanf("%d",&c[i]);
                           ~~~~~^~~~~~~~~~~~
foo.cc:15:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i=1;i<=n;i++) scanf("%d",&d[i]);
                           ~~~~~^~~~~~~~~~~~
foo.cc:19:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d",&x,&y,&w);
         ~~~~~^~~~~~~~~~~~~~~~~~~

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