final boolean[] smallest = new boolean[26];
		final boolean[] largest = new boolean[26];

		Arrays.fill(smallest, Boolean.FALSE);
		Arrays.fill(largest, Boolean.FALSE);

		for (final Character c : s.toCharArray()) {
			if (Character.isLowerCase(c)) {
				final int index = c - 'a';
				smallest[index] = true;
			}
			else {
				final int index = c - 'A';
				largest[index] = true;
			}
		}

		for (int i = 25; i >= 0; i--) {
			if (smallest[i] == true && largest[i] == true) {
				final String res = "" + (char)(i + 65);

				return res;
			}
		}

		return "No";