/in/foo.cc: In function 'bool cmp(std::__cxx11::string, int, int)':
/in/foo.cc:10:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=st;i<s.size();i++)
                  ~^~~~~~~~~
/in/foo.cc: In function 'void dfs(std::__cxx11::string)':
/in/foo.cc:20:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if(a[j].size()<=l-i) continue;          
                ~~~~~~~~~~~^~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:30:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<n;i++) {cin>>a[i]; if(a[i].size()>mx) mx=a[i].size();}
                                         ~~~~~~~~~~~^~~