/in/foo.cc: In function 'int main()':
/in/foo.cc:29:24: error: 'n' was not declared in this scope
  for (long long i=1;i<=n;++i)
                        ^
/in/foo.cc:28:12: warning: unused variable 'k' [-Wunused-variable]
  long long k=strlen(s+1);
            ^