/in/foo.cc: In function 'int main()':
/in/foo.cc:8:5: error: 'cin' was not declared in this scope
     cin.getline(s,1000001);
     ^~~
/in/foo.cc:8:5: note: suggested alternative:
In file included from /in/foo.cc:1:0:
/usr/include/c++/6/iostream:60:18: note:   'std::cin'
   extern istream cin;  /// Linked to standard input
                  ^~~
/in/foo.cc:10:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<=strlen(s)-strlen(ss);++i)
                 ~^~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc:13:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (j=0;j<=strlen(ss)-1;++j)
                  ~^~~~~~~~~~~~~~
/in/foo.cc:20:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(j==strlen(ss)&&(s[j+i]==' '||j+i==strlen(s)))
            ~^~~~~~~~~~~~
/in/foo.cc:20:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(j==strlen(ss)&&(s[j+i]==' '||j+i==strlen(s)))
                                         ~~~^~~~~~~~~~~