/in/foo.cc: In function 'int main()':
/in/foo.cc:14:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<=a.size()/11;i++)
               ~^~~~~~~~~~~~~
/in/foo.cc:17:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (i==a.size()/11)
       ~^~~~~~~~~~~~~
/in/foo.cc:18:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j=i*11;j<a.size();j++)
                   ~^~~~~~~~~
/in/foo.cc:31:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<=a.size()/21;i++)
               ~^~~~~~~~~~~~~
/in/foo.cc:34:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (i==a.size()/21)
       ~^~~~~~~~~~~~~
/in/foo.cc:35:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j=i*21;j<a.size();j++)
                   ~^~~~~~~~~