import java.util.*;

public class Main {
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		ArrayList<String> list = new ArrayList<String>();
		char last = 'X';
		boolean flag = true;
		for (int i = 0; i < n; i++) {
			String s = sc.next();
			if (list.contains(s)) {
				flag = false;
				break;
			} else {
				list.add(s);
			}
			if (i != 0 && s.charAt(0) != last) {
				flag = false;
				break;
			}
			last = s.charAt(s.length() - 1);
		}
		if (flag) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}
	}
	
} import java.util.*; util.* java public class Main {
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		ArrayList<String> list = new ArrayList<String>();
		char last = 'X';
		boolean flag = true;
		for (int i = 0; i < n; i++) {
			String s = sc.next();
			if (list.contains(s)) {
				flag = false;
				break;
			} else {
				list.add(s);
			}
			if (i != 0 && s.charAt(0) != last) {
				flag = false;
				break;
			}
			last = s.charAt(s.length() - 1);
		}
		if (flag) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}
	}
	
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		ArrayList<String> list = new ArrayList<String>();
		char last = 'X';
		boolean flag = true;
		for (int i = 0; i < n; i++) {
			String s = sc.next();
			if (list.contains(s)) {
				flag = false;
				break;
			} else {
				list.add(s);
			}
			if (i != 0 && s.charAt(0) != last) {
				flag = false;
				break;
			}
			last = s.charAt(s.length() - 1);
		}
		if (flag) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		ArrayList<String> list = new ArrayList<String>();
		char last = 'X';
		boolean flag = true;
		for (int i = 0; i < n; i++) {
			String s = sc.next();
			if (list.contains(s)) {
				flag = false;
				break;
			} else {
				list.add(s);
			}
			if (i != 0 && s.charAt(0) != last) {
				flag = false;
				break;
			}
			last = s.charAt(s.length() - 1);
		}
		if (flag) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc ArrayList<String> list = new ArrayList<String>(); list new ArrayList<String>() char last = 'X'; last 'X' boolean flag = true; flag true for (int i = 0; i < n; i++) {
			String s = sc.next();
			if (list.contains(s)) {
				flag = false;
				break;
			} else {
				list.add(s);
			}
			if (i != 0 && s.charAt(0) != last) {
				flag = false;
				break;
			}
			last = s.charAt(s.length() - 1);
		} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
			String s = sc.next();
			if (list.contains(s)) {
				flag = false;
				break;
			} else {
				list.add(s);
			}
			if (i != 0 && s.charAt(0) != last) {
				flag = false;
				break;
			}
			last = s.charAt(s.length() - 1);
		} {
			String s = sc.next();
			if (list.contains(s)) {
				flag = false;
				break;
			} else {
				list.add(s);
			}
			if (i != 0 && s.charAt(0) != last) {
				flag = false;
				break;
			}
			last = s.charAt(s.length() - 1);
		} String s = sc.next(); s sc.next() sc.next sc if (list.contains(s)) {
				flag = false;
				break;
			} else {
				list.add(s);
			} list.contains(s) list.contains list s {
				flag = false;
				break;
			} flag = false flag false break; {
				list.add(s);
			} list.add(s) list.add list s if (i != 0 && s.charAt(0) != last) {
				flag = false;
				break;
			} i != 0 && s.charAt(0) != last i != 0 i 0 s.charAt(0) != last s.charAt(0) s.charAt s 0 last {
				flag = false;
				break;
			} flag = false flag false break; last = s.charAt(s.length() - 1) last s.charAt(s.length() - 1) s.charAt s s.length() - 1 s.length() s.length s 1 if (flag) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		} flag {
			System.out.println("Yes");
		} System.out.println("Yes") System.out.println System.out System System.out "Yes" {
			System.out.println("No");
		} System.out.println("No") System.out.println System.out System System.out "No" String[] args args public class Main {
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		ArrayList<String> list = new ArrayList<String>();
		char last = 'X';
		boolean flag = true;
		for (int i = 0; i < n; i++) {
			String s = sc.next();
			if (list.contains(s)) {
				flag = false;
				break;
			} else {
				list.add(s);
			}
			if (i != 0 && s.charAt(0) != last) {
				flag = false;
				break;
			}
			last = s.charAt(s.length() - 1);
		}
		if (flag) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}
	}
	
} public class Main {
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		ArrayList<String> list = new ArrayList<String>();
		char last = 'X';
		boolean flag = true;
		for (int i = 0; i < n; i++) {
			String s = sc.next();
			if (list.contains(s)) {
				flag = false;
				break;
			} else {
				list.add(s);
			}
			if (i != 0 && s.charAt(0) != last) {
				flag = false;
				break;
			}
			last = s.charAt(s.length() - 1);
		}
		if (flag) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}
	}
	
} Main
import java.util.*;

public class Main {
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		ArrayList<String> list = new ArrayList<String>();
		char last = 'X';
		boolean flag = true;
		for (int i = 0; i < n; i++) {
			String s = sc.next();
			if (list.contains(s)) {
				flag = false;
				break;
			} else {
				list.add(s);
			}
			if (i != 0 && s.charAt(0) != last) {
				flag = false;
				break;
			}
			last = s.charAt(s.length() - 1);
		}
		if (flag) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}
	}
	
}