public static String mergeString(String s1, String s2) {
		StringBuilder rel=new StringBuilder();
		for (int i=0,m=s1.length(),n=s2.length();i<m||i<n;++i)
			if (i<m&&i<n) rel.append(s1.charAt(i)).append(s2.charAt(i));
			else if (i<m) rel.append(s1.charAt(i));
			else rel.append(s2.charAt(i));
		return rel.toString();
	}