code: public static long decode(String s) {
  		long n = 0;
  		for (int i = 0, max = s.length(); i < max; i++) {
  			n = (n * 62) + encoding.indexOf(s.charAt(i));
  		}
  		return n;
  	}
docs: Decode a base62 encoded string into a number (base10). (More expensive than encoding)
  
  @param s the string to decode
  @return the number