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

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		Map<String, String> m = new HashMap<String, String>();
		String preString = sc.next();
		char lastChar = preString.charAt(preString.length() - 1);
		m.put(preString, preString);

		for (int i = 1; i < N; i++) {
			String string = sc.next();
			if (string.charAt(0) != lastChar || m.containsKey(string)) {
				System.out.println("No");
				return;
			}
			lastChar = string.charAt(string.length() - 1);
			m.put(string, string);
		}

		System.out.println("Yes");

		return;
	}
} import java.util.HashMap; HashMap java.util import java.util.Map; Map 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();
		Map<String, String> m = new HashMap<String, String>();
		String preString = sc.next();
		char lastChar = preString.charAt(preString.length() - 1);
		m.put(preString, preString);

		for (int i = 1; i < N; i++) {
			String string = sc.next();
			if (string.charAt(0) != lastChar || m.containsKey(string)) {
				System.out.println("No");
				return;
			}
			lastChar = string.charAt(string.length() - 1);
			m.put(string, string);
		}

		System.out.println("Yes");

		return;
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		Map<String, String> m = new HashMap<String, String>();
		String preString = sc.next();
		char lastChar = preString.charAt(preString.length() - 1);
		m.put(preString, preString);

		for (int i = 1; i < N; i++) {
			String string = sc.next();
			if (string.charAt(0) != lastChar || m.containsKey(string)) {
				System.out.println("No");
				return;
			}
			lastChar = string.charAt(string.length() - 1);
			m.put(string, string);
		}

		System.out.println("Yes");

		return;
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		Map<String, String> m = new HashMap<String, String>();
		String preString = sc.next();
		char lastChar = preString.charAt(preString.length() - 1);
		m.put(preString, preString);

		for (int i = 1; i < N; i++) {
			String string = sc.next();
			if (string.charAt(0) != lastChar || m.containsKey(string)) {
				System.out.println("No");
				return;
			}
			lastChar = string.charAt(string.length() - 1);
			m.put(string, string);
		}

		System.out.println("Yes");

		return;
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc Map<String, String> m = new HashMap<String, String>(); m new HashMap<String, String>() String preString = sc.next(); preString sc.next() sc.next sc char lastChar = preString.charAt(preString.length() - 1); lastChar preString.charAt(preString.length() - 1) preString.charAt preString preString.length() - 1 preString.length() preString.length preString 1 m.put(preString, preString) m.put m preString preString for (int i = 1; i < N; i++) {
			String string = sc.next();
			if (string.charAt(0) != lastChar || m.containsKey(string)) {
				System.out.println("No");
				return;
			}
			lastChar = string.charAt(string.length() - 1);
			m.put(string, string);
		} int i = 1; int i = 1; i 1 i < N i N i++ i++ i {
			String string = sc.next();
			if (string.charAt(0) != lastChar || m.containsKey(string)) {
				System.out.println("No");
				return;
			}
			lastChar = string.charAt(string.length() - 1);
			m.put(string, string);
		} {
			String string = sc.next();
			if (string.charAt(0) != lastChar || m.containsKey(string)) {
				System.out.println("No");
				return;
			}
			lastChar = string.charAt(string.length() - 1);
			m.put(string, string);
		} String string = sc.next(); string sc.next() sc.next sc if (string.charAt(0) != lastChar || m.containsKey(string)) {
				System.out.println("No");
				return;
			} string.charAt(0) != lastChar || m.containsKey(string) string.charAt(0) != lastChar string.charAt(0) string.charAt string 0 lastChar m.containsKey(string) m.containsKey m string {
				System.out.println("No");
				return;
			} System.out.println("No") System.out.println System.out System System.out "No" return; lastChar = string.charAt(string.length() - 1) lastChar string.charAt(string.length() - 1) string.charAt string string.length() - 1 string.length() string.length string 1 m.put(string, string) m.put m string string System.out.println("Yes") System.out.println System.out System System.out "Yes" return; String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		Map<String, String> m = new HashMap<String, String>();
		String preString = sc.next();
		char lastChar = preString.charAt(preString.length() - 1);
		m.put(preString, preString);

		for (int i = 1; i < N; i++) {
			String string = sc.next();
			if (string.charAt(0) != lastChar || m.containsKey(string)) {
				System.out.println("No");
				return;
			}
			lastChar = string.charAt(string.length() - 1);
			m.put(string, string);
		}

		System.out.println("Yes");

		return;
	}
} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		Map<String, String> m = new HashMap<String, String>();
		String preString = sc.next();
		char lastChar = preString.charAt(preString.length() - 1);
		m.put(preString, preString);

		for (int i = 1; i < N; i++) {
			String string = sc.next();
			if (string.charAt(0) != lastChar || m.containsKey(string)) {
				System.out.println("No");
				return;
			}
			lastChar = string.charAt(string.length() - 1);
			m.put(string, string);
		}

		System.out.println("Yes");

		return;
	}
} Main
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		Map<String, String> m = new HashMap<String, String>();
		String preString = sc.next();
		char lastChar = preString.charAt(preString.length() - 1);
		m.put(preString, preString);

		for (int i = 1; i < N; i++) {
			String string = sc.next();
			if (string.charAt(0) != lastChar || m.containsKey(string)) {
				System.out.println("No");
				return;
			}
			lastChar = string.charAt(string.length() - 1);
			m.put(string, string);
		}

		System.out.println("Yes");

		return;
	}
}
