/in/foo.cc: In function 'int main()':
/in/foo.cc:110:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<caozuo.length();i++) 
               ~^~~~~~~~~~~~~~~~
/in/foo.cc:111:7: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if (i!=caozuo.length()-1) putchar(caozuo[i]),putchar(' ');
      ~^~~~~~~~~~~~~~~~~~~