/in/foo.cc: In function 'bool f(int, std::__cxx11::string, std::__cxx11::string)':
/in/foo.cc:10:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<a.size();i++)
              ~^~~~~~~~~
/in/foo.cc:12:15: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   if(a[i]=b[j])
               ^
/in/foo.cc:16:7: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(j==b.size()) return true;
      ~^~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:27:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<b.size();i++)
              ~^~~~~~~~~
/in/foo.cc:29:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<a.size();i++)
              ~^~~~~~~~~