String trim(String s) {
if (s.length() ==0) return s;
if (s.charAt(0) == ' ') return trim(s.substring(1,s.length()));
if (s.charAt(s.length()-1) ==' ') return trim(s.substring(0,s.length()-1));
return s; }
String trim(String s) {
if (s.length() ==0) return s;
if (s.charAt(0) == ' ') return trim(s.substring(1,s.length()));
if (s.charAt(s.length()-1) ==' ') return trim(s.substring(0,s.length()-1));
return s; }