import java.util.*;

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

        int n = sc.nextInt();
        String[] word = new String[n];
        boolean jdg = true;
        for(int i = 0;i < n;i++)
            word[i] = sc.next();

        for(int i = 0;i < n;i++){
            for(int j = i+1;j < n;j++){
                if(word[i].equalsIgnoreCase(word[j])){
                    jdg = false;
                    break;
                }
            }
            if(jdg == false)
            break;
        }

        if(jdg == true){
            for(int i = 0;i < n-1;i++){
                if(word[i].charAt(word[i].length()-1) != word[i+1].charAt(0)){
                    jdg = false;
                    break;
                }
            }
        }
        System.out.println(jdg == true?"Yes" : "No");
        
    }
} import java.util.*; util.* java class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();
        String[] word = new String[n];
        boolean jdg = true;
        for(int i = 0;i < n;i++)
            word[i] = sc.next();

        for(int i = 0;i < n;i++){
            for(int j = i+1;j < n;j++){
                if(word[i].equalsIgnoreCase(word[j])){
                    jdg = false;
                    break;
                }
            }
            if(jdg == false)
            break;
        }

        if(jdg == true){
            for(int i = 0;i < n-1;i++){
                if(word[i].charAt(word[i].length()-1) != word[i+1].charAt(0)){
                    jdg = false;
                    break;
                }
            }
        }
        System.out.println(jdg == true?"Yes" : "No");
        
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();
        String[] word = new String[n];
        boolean jdg = true;
        for(int i = 0;i < n;i++)
            word[i] = sc.next();

        for(int i = 0;i < n;i++){
            for(int j = i+1;j < n;j++){
                if(word[i].equalsIgnoreCase(word[j])){
                    jdg = false;
                    break;
                }
            }
            if(jdg == false)
            break;
        }

        if(jdg == true){
            for(int i = 0;i < n-1;i++){
                if(word[i].charAt(word[i].length()-1) != word[i+1].charAt(0)){
                    jdg = false;
                    break;
                }
            }
        }
        System.out.println(jdg == true?"Yes" : "No");
        
    } main {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();
        String[] word = new String[n];
        boolean jdg = true;
        for(int i = 0;i < n;i++)
            word[i] = sc.next();

        for(int i = 0;i < n;i++){
            for(int j = i+1;j < n;j++){
                if(word[i].equalsIgnoreCase(word[j])){
                    jdg = false;
                    break;
                }
            }
            if(jdg == false)
            break;
        }

        if(jdg == true){
            for(int i = 0;i < n-1;i++){
                if(word[i].charAt(word[i].length()-1) != word[i+1].charAt(0)){
                    jdg = false;
                    break;
                }
            }
        }
        System.out.println(jdg == true?"Yes" : "No");
        
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc String[] word = new String[n]; word new String[n] n boolean jdg = true; jdg true for(int i = 0;i < n;i++)
            word[i] = sc.next(); int i = 0; int i = 0; i 0 i < n i n i++ i++ i word[i] = sc.next(); word[i] = sc.next() word[i] word i sc.next() sc.next sc for(int i = 0;i < n;i++){
            for(int j = i+1;j < n;j++){
                if(word[i].equalsIgnoreCase(word[j])){
                    jdg = false;
                    break;
                }
            }
            if(jdg == false)
            break;
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            for(int j = i+1;j < n;j++){
                if(word[i].equalsIgnoreCase(word[j])){
                    jdg = false;
                    break;
                }
            }
            if(jdg == false)
            break;
        } {
            for(int j = i+1;j < n;j++){
                if(word[i].equalsIgnoreCase(word[j])){
                    jdg = false;
                    break;
                }
            }
            if(jdg == false)
            break;
        } for(int j = i+1;j < n;j++){
                if(word[i].equalsIgnoreCase(word[j])){
                    jdg = false;
                    break;
                }
            } int j = i+1; int j = i+1; j i+1 i 1 j < n j n j++ j++ j {
                if(word[i].equalsIgnoreCase(word[j])){
                    jdg = false;
                    break;
                }
            } {
                if(word[i].equalsIgnoreCase(word[j])){
                    jdg = false;
                    break;
                }
            } if(word[i].equalsIgnoreCase(word[j])){
                    jdg = false;
                    break;
                } word[i].equalsIgnoreCase(word[j]) word[i].equalsIgnoreCase word[i] word i word[j] word j {
                    jdg = false;
                    break;
                } jdg = false jdg false break; if(jdg == false)
            break; jdg == false jdg false break; if(jdg == true){
            for(int i = 0;i < n-1;i++){
                if(word[i].charAt(word[i].length()-1) != word[i+1].charAt(0)){
                    jdg = false;
                    break;
                }
            }
        } jdg == true jdg true {
            for(int i = 0;i < n-1;i++){
                if(word[i].charAt(word[i].length()-1) != word[i+1].charAt(0)){
                    jdg = false;
                    break;
                }
            }
        } for(int i = 0;i < n-1;i++){
                if(word[i].charAt(word[i].length()-1) != word[i+1].charAt(0)){
                    jdg = false;
                    break;
                }
            } int i = 0; int i = 0; i 0 i < n-1 i n-1 n 1 i++ i++ i {
                if(word[i].charAt(word[i].length()-1) != word[i+1].charAt(0)){
                    jdg = false;
                    break;
                }
            } {
                if(word[i].charAt(word[i].length()-1) != word[i+1].charAt(0)){
                    jdg = false;
                    break;
                }
            } if(word[i].charAt(word[i].length()-1) != word[i+1].charAt(0)){
                    jdg = false;
                    break;
                } word[i].charAt(word[i].length()-1) != word[i+1].charAt(0) word[i].charAt(word[i].length()-1) word[i].charAt word[i] word i word[i].length()-1 word[i].length() word[i].length word[i] word i 1 word[i+1].charAt(0) word[i+1].charAt word[i+1] word i+1 i 1 0 {
                    jdg = false;
                    break;
                } jdg = false jdg false break; System.out.println(jdg == true?"Yes" : "No") System.out.println System.out System System.out jdg == true?"Yes" : "No" jdg == true jdg true "Yes" "No" String[] args args
import java.util.*;

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

        int n = sc.nextInt();
        String[] word = new String[n];
        boolean jdg = true;
        for(int i = 0;i < n;i++)
            word[i] = sc.next();

        for(int i = 0;i < n;i++){
            for(int j = i+1;j < n;j++){
                if(word[i].equalsIgnoreCase(word[j])){
                    jdg = false;
                    break;
                }
            }
            if(jdg == false)
            break;
        }

        if(jdg == true){
            for(int i = 0;i < n-1;i++){
                if(word[i].charAt(word[i].length()-1) != word[i+1].charAt(0)){
                    jdg = false;
                    break;
                }
            }
        }
        System.out.println(jdg == true?"Yes" : "No");
        
    }
}