

import java.util.*;

public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int N = scanner.nextInt();
		String output = "Yes";
		
		String[] W = new String[N];
		
		HashMap<String, Boolean> hmap = new HashMap<String, Boolean>();
		
		for(int i=0; i<N; i++) {
			W[i] = scanner.next();
			
			if(hmap.get(W[i]) != null)
				output = "No";
			hmap.put(W[i], true);
			
			if((i!=0) && (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))))
				output = "No";
			
		}
		
		System.out.println(output);
		

	}

} import java.util.*; util.* java public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int N = scanner.nextInt();
		String output = "Yes";
		
		String[] W = new String[N];
		
		HashMap<String, Boolean> hmap = new HashMap<String, Boolean>();
		
		for(int i=0; i<N; i++) {
			W[i] = scanner.next();
			
			if(hmap.get(W[i]) != null)
				output = "No";
			hmap.put(W[i], true);
			
			if((i!=0) && (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))))
				output = "No";
			
		}
		
		System.out.println(output);
		

	}

} Main public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int N = scanner.nextInt();
		String output = "Yes";
		
		String[] W = new String[N];
		
		HashMap<String, Boolean> hmap = new HashMap<String, Boolean>();
		
		for(int i=0; i<N; i++) {
			W[i] = scanner.next();
			
			if(hmap.get(W[i]) != null)
				output = "No";
			hmap.put(W[i], true);
			
			if((i!=0) && (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))))
				output = "No";
			
		}
		
		System.out.println(output);
		

	} main {
		Scanner scanner = new Scanner(System.in);
		int N = scanner.nextInt();
		String output = "Yes";
		
		String[] W = new String[N];
		
		HashMap<String, Boolean> hmap = new HashMap<String, Boolean>();
		
		for(int i=0; i<N; i++) {
			W[i] = scanner.next();
			
			if(hmap.get(W[i]) != null)
				output = "No";
			hmap.put(W[i], true);
			
			if((i!=0) && (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))))
				output = "No";
			
		}
		
		System.out.println(output);
		

	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int N = scanner.nextInt(); N scanner.nextInt() scanner.nextInt scanner String output = "Yes"; output "Yes" String[] W = new String[N]; W new String[N] N HashMap<String, Boolean> hmap = new HashMap<String, Boolean>(); hmap new HashMap<String, Boolean>() for(int i=0; i<N; i++) {
			W[i] = scanner.next();
			
			if(hmap.get(W[i]) != null)
				output = "No";
			hmap.put(W[i], true);
			
			if((i!=0) && (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))))
				output = "No";
			
		} int i=0; int i=0; i 0 i<N i N i++ i++ i {
			W[i] = scanner.next();
			
			if(hmap.get(W[i]) != null)
				output = "No";
			hmap.put(W[i], true);
			
			if((i!=0) && (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))))
				output = "No";
			
		} {
			W[i] = scanner.next();
			
			if(hmap.get(W[i]) != null)
				output = "No";
			hmap.put(W[i], true);
			
			if((i!=0) && (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))))
				output = "No";
			
		} W[i] = scanner.next() W[i] W i scanner.next() scanner.next scanner if(hmap.get(W[i]) != null)
				output = "No"; hmap.get(W[i]) != null hmap.get(W[i]) hmap.get hmap W[i] W i null output = "No" output "No" hmap.put(W[i], true) hmap.put hmap W[i] W i true if((i!=0) && (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))))
				output = "No"; (i!=0) && (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))) (i!=0) i 0 (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))) W[i].charAt(0) W[i].charAt W[i] W i 0 (W[i-1].charAt(W[i-1].length()-1)) W[i-1].charAt W[i-1] W i-1 i 1 W[i-1].length()-1 W[i-1].length() W[i-1].length W[i-1] W i-1 i 1 1 output = "No" output "No" System.out.println(output) System.out.println System.out System System.out output String[] args args public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int N = scanner.nextInt();
		String output = "Yes";
		
		String[] W = new String[N];
		
		HashMap<String, Boolean> hmap = new HashMap<String, Boolean>();
		
		for(int i=0; i<N; i++) {
			W[i] = scanner.next();
			
			if(hmap.get(W[i]) != null)
				output = "No";
			hmap.put(W[i], true);
			
			if((i!=0) && (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))))
				output = "No";
			
		}
		
		System.out.println(output);
		

	}

} public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int N = scanner.nextInt();
		String output = "Yes";
		
		String[] W = new String[N];
		
		HashMap<String, Boolean> hmap = new HashMap<String, Boolean>();
		
		for(int i=0; i<N; i++) {
			W[i] = scanner.next();
			
			if(hmap.get(W[i]) != null)
				output = "No";
			hmap.put(W[i], true);
			
			if((i!=0) && (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))))
				output = "No";
			
		}
		
		System.out.println(output);
		

	}

} Main


import java.util.*;

public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int N = scanner.nextInt();
		String output = "Yes";
		
		String[] W = new String[N];
		
		HashMap<String, Boolean> hmap = new HashMap<String, Boolean>();
		
		for(int i=0; i<N; i++) {
			W[i] = scanner.next();
			
			if(hmap.get(W[i]) != null)
				output = "No";
			hmap.put(W[i], true);
			
			if((i!=0) && (W[i].charAt(0) != (W[i-1].charAt(W[i-1].length()-1))))
				output = "No";
			
		}
		
		System.out.println(output);
		

	}

}
