import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.List;
import java.util.Arrays;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author hakamada
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC109_2 solver = new ABC109_2();
        solver.solve(1, in, out);
        out.close();
    }

    static class ABC109_2 {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            String[] W = new String[N];

            for (int i = 0; i < N; i++) {
                W[i] = in.next();
            }
            boolean dup = false;

            for (int i = 0; i < W.length; i++) {
                String val = W[i];
                W[i] = "_" + W[i];
                if (Arrays.asList(W).contains(val)) {
                    out.println("No");
                    return;
                }
                if (i > 0) {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                }
            }
            out.println("Yes");

        }

    }
}
 import java.io.OutputStream; OutputStream java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.List; List java.util import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC109_2 solver = new ABC109_2();
        solver.solve(1, in, out);
        out.close();
    }

    static class ABC109_2 {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            String[] W = new String[N];

            for (int i = 0; i < N; i++) {
                W[i] = in.next();
            }
            boolean dup = false;

            for (int i = 0; i < W.length; i++) {
                String val = W[i];
                W[i] = "_" + W[i];
                if (Arrays.asList(W).contains(val)) {
                    out.println("No");
                    return;
                }
                if (i > 0) {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                }
            }
            out.println("Yes");

        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC109_2 solver = new ABC109_2();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC109_2 solver = new ABC109_2();
        solver.solve(1, in, out);
        out.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out Scanner in = new Scanner(inputStream); in new Scanner(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) ABC109_2 solver = new ABC109_2(); solver new ABC109_2() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class ABC109_2 {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            String[] W = new String[N];

            for (int i = 0; i < N; i++) {
                W[i] = in.next();
            }
            boolean dup = false;

            for (int i = 0; i < W.length; i++) {
                String val = W[i];
                W[i] = "_" + W[i];
                if (Arrays.asList(W).contains(val)) {
                    out.println("No");
                    return;
                }
                if (i > 0) {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                }
            }
            out.println("Yes");

        }

    } ABC109_2 public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            String[] W = new String[N];

            for (int i = 0; i < N; i++) {
                W[i] = in.next();
            }
            boolean dup = false;

            for (int i = 0; i < W.length; i++) {
                String val = W[i];
                W[i] = "_" + W[i];
                if (Arrays.asList(W).contains(val)) {
                    out.println("No");
                    return;
                }
                if (i > 0) {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                }
            }
            out.println("Yes");

        } solve {
            int N = in.nextInt();
            String[] W = new String[N];

            for (int i = 0; i < N; i++) {
                W[i] = in.next();
            }
            boolean dup = false;

            for (int i = 0; i < W.length; i++) {
                String val = W[i];
                W[i] = "_" + W[i];
                if (Arrays.asList(W).contains(val)) {
                    out.println("No");
                    return;
                }
                if (i > 0) {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                }
            }
            out.println("Yes");

        } int N = in.nextInt(); N in.nextInt() in.nextInt in String[] W = new String[N]; W new String[N] N for (int i = 0; i < N; i++) {
                W[i] = in.next();
            } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
                W[i] = in.next();
            } {
                W[i] = in.next();
            } W[i] = in.next() W[i] W i in.next() in.next in boolean dup = false; dup false for (int i = 0; i < W.length; i++) {
                String val = W[i];
                W[i] = "_" + W[i];
                if (Arrays.asList(W).contains(val)) {
                    out.println("No");
                    return;
                }
                if (i > 0) {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                }
            } int i = 0; int i = 0; i 0 i < W.length i W.length W W.length i++ i++ i {
                String val = W[i];
                W[i] = "_" + W[i];
                if (Arrays.asList(W).contains(val)) {
                    out.println("No");
                    return;
                }
                if (i > 0) {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                }
            } {
                String val = W[i];
                W[i] = "_" + W[i];
                if (Arrays.asList(W).contains(val)) {
                    out.println("No");
                    return;
                }
                if (i > 0) {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                }
            } String val = W[i]; val W[i] W i W[i] = "_" + W[i] W[i] W i "_" + W[i] "_" W[i] W i if (Arrays.asList(W).contains(val)) {
                    out.println("No");
                    return;
                } Arrays.asList(W).contains(val) Arrays.asList(W).contains Arrays.asList(W) Arrays.asList Arrays W val {
                    out.println("No");
                    return;
                } out.println("No") out.println out "No" return; if (i > 0) {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                } i > 0 i 0 {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                } if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    } W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0 W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) W[i - 1].substring(W[i - 1].length() - 1).compareTo W[i - 1].substring(W[i - 1].length() - 1) W[i - 1].substring 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 val.substring(0, 1) val.substring val 0 1 0 {
                        out.println("No");
                        return;
                    } out.println("No") out.println out "No" return; out.println("Yes") out.println out "Yes" int testNumber testNumber Scanner in in PrintWriter out out public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC109_2 solver = new ABC109_2();
        solver.solve(1, in, out);
        out.close();
    }

    static class ABC109_2 {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            String[] W = new String[N];

            for (int i = 0; i < N; i++) {
                W[i] = in.next();
            }
            boolean dup = false;

            for (int i = 0; i < W.length; i++) {
                String val = W[i];
                W[i] = "_" + W[i];
                if (Arrays.asList(W).contains(val)) {
                    out.println("No");
                    return;
                }
                if (i > 0) {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                }
            }
            out.println("Yes");

        }

    }
} public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC109_2 solver = new ABC109_2();
        solver.solve(1, in, out);
        out.close();
    }

    static class ABC109_2 {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            String[] W = new String[N];

            for (int i = 0; i < N; i++) {
                W[i] = in.next();
            }
            boolean dup = false;

            for (int i = 0; i < W.length; i++) {
                String val = W[i];
                W[i] = "_" + W[i];
                if (Arrays.asList(W).contains(val)) {
                    out.println("No");
                    return;
                }
                if (i > 0) {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                }
            }
            out.println("Yes");

        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.List;
import java.util.Arrays;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author hakamada
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC109_2 solver = new ABC109_2();
        solver.solve(1, in, out);
        out.close();
    }

    static class ABC109_2 {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            String[] W = new String[N];

            for (int i = 0; i < N; i++) {
                W[i] = in.next();
            }
            boolean dup = false;

            for (int i = 0; i < W.length; i++) {
                String val = W[i];
                W[i] = "_" + W[i];
                if (Arrays.asList(W).contains(val)) {
                    out.println("No");
                    return;
                }
                if (i > 0) {
                    if (W[i - 1].substring(W[i - 1].length() - 1).compareTo(val.substring(0, 1)) != 0) {
                        out.println("No");
                        return;
                    }
                }
            }
            out.println("Yes");

        }

    }
}

