import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		char[] s = br.readLine().toCharArray();
		br.close();
		for (int i = 0; i < s.length; i++) {
			int a = s[i] - 'a';
			if (a < 0 || 25 < a || s[i] != ' ') {
				return;
			}
		}

		for (int i = 0; i < s.length - 2; i++) {
			label:
			for (int j = i + 2; j < s.length; j++) {
				int[] blank = new int[100000];
				for (int k = 0; k < i; k++) {
					if (s[k] != ' ' && s[k] != '　') {
						blank[s[k] - 'a'] = 1;
					}
				}
				for (int k = j; k < s.length; k++) {
					if (s[k] != ' ' && s[k] != '　') {
						blank[s[k] - 'a'] = 1;
					}
				}
				for (int k = i; k < j; k++) {
					if ((k - i) % 2 == 0) {
						if (s[k] == ' ' || s[k] == '　' || blank[s[k] - 'a'] == 1) {
							continue label;
						} else {
							blank[s[k] - 'a'] = 2;
						}
					} else {
						if (s[k] != ' ' && s[k] != '　') {
							if (blank[s[k] - 'a'] == 2) {
								continue label;
							} else {
								blank[s[k] - 'a'] = 1;
							}
						}
					}
				}
				System.out.println("Yes");
				return;
			}
		}
		System.out.println("NO");
	}
}