/in/foo.cc: In function 'void couts()':
/in/foo.cc:8:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<s.size();i++)
               ~^~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:50:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      while ((P=s.find(b,P))!=string::npos)
             ~~~~~~~~~~~~~~~^~~~~~~~
/in/foo.cc:57:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      while ((P=s.find(f1,P))!=string::npos)
             ~~~~~~~~~~~~~~~~^~~~~~~~
/in/foo.cc:67:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i=abs(n-m)-1;i<a.size();i++) 
                         ~^~~~~~~~~