/in/foo.cc: In function 'int main()':
/in/foo.cc:10:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<=strlen(b);i++)
              ~^~~~~~~~~~~
/in/foo.cc:15:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<=strlen(a);i++)
              ~^~~~~~~~~~~