/in/foo.cc: In function 'int main()':
/in/foo.cc:8:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<k.length();i++)
               ~^~~~~~~~~~~
/in/foo.cc:13:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0,j=0;i<coded.length();i++,j++)
                   ~^~~~~~~~~~~~~~~
/in/foo.cc:15:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (j==k.length()) j=0;
       ~^~~~~~~~~~~~