compareto in java string
******Java String compareTo()******
  The Java String class compareTo() method compares the given 
  string with the current string lexicographically. 
  It returns a positive number, negative number, or 0.
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  	if s1 > s2, it returns positive number  
	if s1 < s2, it returns negative number  
	if s1 == s2, it returns 0  
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