/in/foo.cc: In function 'int main()':
/in/foo.cc:33:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while(i<strlen(aa) && i<strlen(bb))
        ~^~~~~~~~~~~
/in/foo.cc:33:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while(i<strlen(aa) && i<strlen(bb))
                        ~^~~~~~~~~~~
/in/foo.cc:48:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while(i<strlen(aa))
        ~^~~~~~~~~~~
/in/foo.cc:53:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while(i<strlen(aa))
        ~^~~~~~~~~~~