/in/foo.cc: In function 'int main()':
/in/foo.cc:13:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<strlen(a);i++)
              ~^~~~~~~~~~
/in/foo.cc:31:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<strlen(a);i++)
              ~^~~~~~~~~~
/in/foo.cc:11:9: warning: unused variable 'len' [-Wunused-variable]
     int len = 0; int w=0,l=0;
         ^~~