import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }

        int left = 0;
        int count = 0;

        while (left < arr.length) {
            if (arr[left] == 0) left++;
            else {
                int right = left;

                while (right < arr.length && arr[right] != 0) {
                    arr[right++]--;
                }
                count++;
            }
        }
        System.out.println(count);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }

        int left = 0;
        int count = 0;

        while (left < arr.length) {
            if (arr[left] == 0) left++;
            else {
                int right = left;

                while (right < arr.length && arr[right] != 0) {
                    arr[right++]--;
                }
                count++;
            }
        }
        System.out.println(count);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }

        int left = 0;
        int count = 0;

        while (left < arr.length) {
            if (arr[left] == 0) left++;
            else {
                int right = left;

                while (right < arr.length && arr[right] != 0) {
                    arr[right++]--;
                }
                count++;
            }
        }
        System.out.println(count);
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }

        int left = 0;
        int count = 0;

        while (left < arr.length) {
            if (arr[left] == 0) left++;
            else {
                int right = left;

                while (right < arr.length && arr[right] != 0) {
                    arr[right++]--;
                }
                count++;
            }
        }
        System.out.println(count);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int[] arr = new int[n]; arr new int[n] n for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            arr[i] = sc.nextInt();
        } {
            arr[i] = sc.nextInt();
        } arr[i] = sc.nextInt() arr[i] arr i sc.nextInt() sc.nextInt sc int left = 0; left 0 int count = 0; count 0 while (left < arr.length) {
            if (arr[left] == 0) left++;
            else {
                int right = left;

                while (right < arr.length && arr[right] != 0) {
                    arr[right++]--;
                }
                count++;
            }
        } left < arr.length left arr.length arr arr.length {
            if (arr[left] == 0) left++;
            else {
                int right = left;

                while (right < arr.length && arr[right] != 0) {
                    arr[right++]--;
                }
                count++;
            }
        } if (arr[left] == 0) left++;
            else {
                int right = left;

                while (right < arr.length && arr[right] != 0) {
                    arr[right++]--;
                }
                count++;
            } arr[left] == 0 arr[left] arr left 0 left++ left {
                int right = left;

                while (right < arr.length && arr[right] != 0) {
                    arr[right++]--;
                }
                count++;
            } int right = left; right left while (right < arr.length && arr[right] != 0) {
                    arr[right++]--;
                } right < arr.length && arr[right] != 0 right < arr.length right arr.length arr arr.length arr[right] != 0 arr[right] arr right 0 {
                    arr[right++]--;
                } arr[right++]-- arr[right++] arr right++ right count++ count System.out.println(count) System.out.println System.out System System.out count String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }

        int left = 0;
        int count = 0;

        while (left < arr.length) {
            if (arr[left] == 0) left++;
            else {
                int right = left;

                while (right < arr.length && arr[right] != 0) {
                    arr[right++]--;
                }
                count++;
            }
        }
        System.out.println(count);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }

        int left = 0;
        int count = 0;

        while (left < arr.length) {
            if (arr[left] == 0) left++;
            else {
                int right = left;

                while (right < arr.length && arr[right] != 0) {
                    arr[right++]--;
                }
                count++;
            }
        }
        System.out.println(count);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }

        int left = 0;
        int count = 0;

        while (left < arr.length) {
            if (arr[left] == 0) left++;
            else {
                int right = left;

                while (right < arr.length && arr[right] != 0) {
                    arr[right++]--;
                }
                count++;
            }
        }
        System.out.println(count);
    }
}