import java.util.Scanner;

public class Main {

  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();

    int[] h = new int[n];

    h[0] = sc.nextInt();
    int max = h[0];
    for (int i = 1; i < n; ++i) {
      h[i] = sc.nextInt();
      max = (h[i] > max) ? h[i] : max;

      if (h[i] <= max - 2) {
        System.out.println("No");
        System.exit(0);
      }
    }

    System.out.println("Yes");
  }
} 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();

    int[] h = new int[n];

    h[0] = sc.nextInt();
    int max = h[0];
    for (int i = 1; i < n; ++i) {
      h[i] = sc.nextInt();
      max = (h[i] > max) ? h[i] : max;

      if (h[i] <= max - 2) {
        System.out.println("No");
        System.exit(0);
      }
    }

    System.out.println("Yes");
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();

    int[] h = new int[n];

    h[0] = sc.nextInt();
    int max = h[0];
    for (int i = 1; i < n; ++i) {
      h[i] = sc.nextInt();
      max = (h[i] > max) ? h[i] : max;

      if (h[i] <= max - 2) {
        System.out.println("No");
        System.exit(0);
      }
    }

    System.out.println("Yes");
  } main {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();

    int[] h = new int[n];

    h[0] = sc.nextInt();
    int max = h[0];
    for (int i = 1; i < n; ++i) {
      h[i] = sc.nextInt();
      max = (h[i] > max) ? h[i] : max;

      if (h[i] <= max - 2) {
        System.out.println("No");
        System.exit(0);
      }
    }

    System.out.println("Yes");
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int[] h = new int[n]; h new int[n] n h[0] = sc.nextInt() h[0] h 0 sc.nextInt() sc.nextInt sc int max = h[0]; max h[0] h 0 for (int i = 1; i < n; ++i) {
      h[i] = sc.nextInt();
      max = (h[i] > max) ? h[i] : max;

      if (h[i] <= max - 2) {
        System.out.println("No");
        System.exit(0);
      }
    } int i = 1; int i = 1; i 1 i < n i n ++i ++i i {
      h[i] = sc.nextInt();
      max = (h[i] > max) ? h[i] : max;

      if (h[i] <= max - 2) {
        System.out.println("No");
        System.exit(0);
      }
    } {
      h[i] = sc.nextInt();
      max = (h[i] > max) ? h[i] : max;

      if (h[i] <= max - 2) {
        System.out.println("No");
        System.exit(0);
      }
    } h[i] = sc.nextInt() h[i] h i sc.nextInt() sc.nextInt sc max = (h[i] > max) ? h[i] : max max (h[i] > max) ? h[i] : max (h[i] > max) h[i] h i max h[i] h i max if (h[i] <= max - 2) {
        System.out.println("No");
        System.exit(0);
      } h[i] <= max - 2 h[i] h i max - 2 max 2 {
        System.out.println("No");
        System.exit(0);
      } System.out.println("No") System.out.println System.out System System.out "No" System.exit(0) System.exit System 0 System.out.println("Yes") System.out.println System.out System System.out "Yes" String[] args args public class Main {

  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();

    int[] h = new int[n];

    h[0] = sc.nextInt();
    int max = h[0];
    for (int i = 1; i < n; ++i) {
      h[i] = sc.nextInt();
      max = (h[i] > max) ? h[i] : max;

      if (h[i] <= max - 2) {
        System.out.println("No");
        System.exit(0);
      }
    }

    System.out.println("Yes");
  }
} public class Main {

  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();

    int[] h = new int[n];

    h[0] = sc.nextInt();
    int max = h[0];
    for (int i = 1; i < n; ++i) {
      h[i] = sc.nextInt();
      max = (h[i] > max) ? h[i] : max;

      if (h[i] <= max - 2) {
        System.out.println("No");
        System.exit(0);
      }
    }

    System.out.println("Yes");
  }
} Main
import java.util.Scanner;

public class Main {

  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();

    int[] h = new int[n];

    h[0] = sc.nextInt();
    int max = h[0];
    for (int i = 1; i < n; ++i) {
      h[i] = sc.nextInt();
      max = (h[i] > max) ? h[i] : max;

      if (h[i] <= max - 2) {
        System.out.println("No");
        System.exit(0);
      }
    }

    System.out.println("Yes");
  }
}