

import java.util.HashMap;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		String w = sc.next();
		String last = w.substring(w.length() - 1, w.length());
		HashMap<String, String> wordList = new HashMap<String, String>();
		String ans = "Yes";
		wordList.put(w, w);

		for (int i = 1; i < n; i++) {
			w = sc.next();
			if (!last.equals(w.substring(0, 1)))
				ans = "No";
			if (wordList.containsKey(w))
				ans = "No";
			else
				wordList.put(w, w);
			last = w.substring(w.length() - 1, w.length());
		}
		System.out.println(ans);

	}

} import java.util.HashMap; HashMap java.util import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		String w = sc.next();
		String last = w.substring(w.length() - 1, w.length());
		HashMap<String, String> wordList = new HashMap<String, String>();
		String ans = "Yes";
		wordList.put(w, w);

		for (int i = 1; i < n; i++) {
			w = sc.next();
			if (!last.equals(w.substring(0, 1)))
				ans = "No";
			if (wordList.containsKey(w))
				ans = "No";
			else
				wordList.put(w, w);
			last = w.substring(w.length() - 1, w.length());
		}
		System.out.println(ans);

	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		String w = sc.next();
		String last = w.substring(w.length() - 1, w.length());
		HashMap<String, String> wordList = new HashMap<String, String>();
		String ans = "Yes";
		wordList.put(w, w);

		for (int i = 1; i < n; i++) {
			w = sc.next();
			if (!last.equals(w.substring(0, 1)))
				ans = "No";
			if (wordList.containsKey(w))
				ans = "No";
			else
				wordList.put(w, w);
			last = w.substring(w.length() - 1, w.length());
		}
		System.out.println(ans);

	} main {
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		String w = sc.next();
		String last = w.substring(w.length() - 1, w.length());
		HashMap<String, String> wordList = new HashMap<String, String>();
		String ans = "Yes";
		wordList.put(w, w);

		for (int i = 1; i < n; i++) {
			w = sc.next();
			if (!last.equals(w.substring(0, 1)))
				ans = "No";
			if (wordList.containsKey(w))
				ans = "No";
			else
				wordList.put(w, w);
			last = w.substring(w.length() - 1, w.length());
		}
		System.out.println(ans);

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc String w = sc.next(); w sc.next() sc.next sc String last = w.substring(w.length() - 1, w.length()); last w.substring(w.length() - 1, w.length()) w.substring w w.length() - 1 w.length() w.length w 1 w.length() w.length w HashMap<String, String> wordList = new HashMap<String, String>(); wordList new HashMap<String, String>() String ans = "Yes"; ans "Yes" wordList.put(w, w) wordList.put wordList w w for (int i = 1; i < n; i++) {
			w = sc.next();
			if (!last.equals(w.substring(0, 1)))
				ans = "No";
			if (wordList.containsKey(w))
				ans = "No";
			else
				wordList.put(w, w);
			last = w.substring(w.length() - 1, w.length());
		} int i = 1; int i = 1; i 1 i < n i n i++ i++ i {
			w = sc.next();
			if (!last.equals(w.substring(0, 1)))
				ans = "No";
			if (wordList.containsKey(w))
				ans = "No";
			else
				wordList.put(w, w);
			last = w.substring(w.length() - 1, w.length());
		} {
			w = sc.next();
			if (!last.equals(w.substring(0, 1)))
				ans = "No";
			if (wordList.containsKey(w))
				ans = "No";
			else
				wordList.put(w, w);
			last = w.substring(w.length() - 1, w.length());
		} w = sc.next() w sc.next() sc.next sc if (!last.equals(w.substring(0, 1)))
				ans = "No"; !last.equals(w.substring(0, 1)) last.equals(w.substring(0, 1)) last.equals last w.substring(0, 1) w.substring w 0 1 ans = "No" ans "No" if (wordList.containsKey(w))
				ans = "No";
			else
				wordList.put(w, w); wordList.containsKey(w) wordList.containsKey wordList w ans = "No" ans "No" wordList.put(w, w) wordList.put wordList w w last = w.substring(w.length() - 1, w.length()) last w.substring(w.length() - 1, w.length()) w.substring w w.length() - 1 w.length() w.length w 1 w.length() w.length w System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		String w = sc.next();
		String last = w.substring(w.length() - 1, w.length());
		HashMap<String, String> wordList = new HashMap<String, String>();
		String ans = "Yes";
		wordList.put(w, w);

		for (int i = 1; i < n; i++) {
			w = sc.next();
			if (!last.equals(w.substring(0, 1)))
				ans = "No";
			if (wordList.containsKey(w))
				ans = "No";
			else
				wordList.put(w, w);
			last = w.substring(w.length() - 1, w.length());
		}
		System.out.println(ans);

	}

} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		String w = sc.next();
		String last = w.substring(w.length() - 1, w.length());
		HashMap<String, String> wordList = new HashMap<String, String>();
		String ans = "Yes";
		wordList.put(w, w);

		for (int i = 1; i < n; i++) {
			w = sc.next();
			if (!last.equals(w.substring(0, 1)))
				ans = "No";
			if (wordList.containsKey(w))
				ans = "No";
			else
				wordList.put(w, w);
			last = w.substring(w.length() - 1, w.length());
		}
		System.out.println(ans);

	}

} Main


import java.util.HashMap;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		String w = sc.next();
		String last = w.substring(w.length() - 1, w.length());
		HashMap<String, String> wordList = new HashMap<String, String>();
		String ans = "Yes";
		wordList.put(w, w);

		for (int i = 1; i < n; i++) {
			w = sc.next();
			if (!last.equals(w.substring(0, 1)))
				ans = "No";
			if (wordList.containsKey(w))
				ans = "No";
			else
				wordList.put(w, w);
			last = w.substring(w.length() - 1, w.length());
		}
		System.out.println(ans);

	}

}
