foo.cc: In function 'int main()':
foo.cc:22:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<v[i].size();++j)
               ~^~~~~~~~~~~~
foo.cc:24:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int k=j+1;k<v[i].size();++k)
                  ~^~~~~~~~~~~~
foo.cc:12:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m);
  ~~~~~^~~~~~~~~~~~~~
foo.cc:14:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&id[i]);
   ~~~~~^~~~~~~~~~~~~
foo.cc:17:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&col[i]);
   ~~~~~^~~~~~~~~~~~~~

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