import 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];

        for(int i = 0; i < n; i++){
            h[i] = sc.nextInt();
        }

        int ans = 0;

        for(int i = 0; i < n; i++){
            while(h[i] != 0){
                for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                }
                ans++;
            }
        }
        
        System.out.println(ans);

    }
} 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[] h = new int [n];

        for(int i = 0; i < n; i++){
            h[i] = sc.nextInt();
        }

        int ans = 0;

        for(int i = 0; i < n; i++){
            while(h[i] != 0){
                for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                }
                ans++;
            }
        }
        
        System.out.println(ans);

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

        int n = sc.nextInt();

        int[] h = new int [n];

        for(int i = 0; i < n; i++){
            h[i] = sc.nextInt();
        }

        int ans = 0;

        for(int i = 0; i < n; i++){
            while(h[i] != 0){
                for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                }
                ans++;
            }
        }
        
        System.out.println(ans);

    } main {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();

        int[] h = new int [n];

        for(int i = 0; i < n; i++){
            h[i] = sc.nextInt();
        }

        int ans = 0;

        for(int i = 0; i < n; i++){
            while(h[i] != 0){
                for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                }
                ans++;
            }
        }
        
        System.out.println(ans);

    } 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 for(int i = 0; i < n; i++){
            h[i] = sc.nextInt();
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            h[i] = sc.nextInt();
        } {
            h[i] = sc.nextInt();
        } h[i] = sc.nextInt() h[i] h i sc.nextInt() sc.nextInt sc int ans = 0; ans 0 for(int i = 0; i < n; i++){
            while(h[i] != 0){
                for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                }
                ans++;
            }
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            while(h[i] != 0){
                for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                }
                ans++;
            }
        } {
            while(h[i] != 0){
                for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                }
                ans++;
            }
        } while(h[i] != 0){
                for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                }
                ans++;
            } h[i] != 0 h[i] h i 0 {
                for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                }
                ans++;
            } for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                } int j = i; int j = i; j i j < n && h[j] != 0 j < n j n h[j] != 0 h[j] h j 0 j++ j++ j {
                    h[j]--;
                } {
                    h[j]--;
                } h[j]-- h[j] h j ans++ ans System.out.println(ans) System.out.println System.out System System.out ans 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];

        for(int i = 0; i < n; i++){
            h[i] = sc.nextInt();
        }

        int ans = 0;

        for(int i = 0; i < n; i++){
            while(h[i] != 0){
                for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                }
                ans++;
            }
        }
        
        System.out.println(ans);

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

        int n = sc.nextInt();

        int[] h = new int [n];

        for(int i = 0; i < n; i++){
            h[i] = sc.nextInt();
        }

        int ans = 0;

        for(int i = 0; i < n; i++){
            while(h[i] != 0){
                for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                }
                ans++;
            }
        }
        
        System.out.println(ans);

    }
} Main
import 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];

        for(int i = 0; i < n; i++){
            h[i] = sc.nextInt();
        }

        int ans = 0;

        for(int i = 0; i < n; i++){
            while(h[i] != 0){
                for(int j = i; j < n && h[j] != 0; j++){
                    h[j]--;
                }
                ans++;
            }
        }
        
        System.out.println(ans);

    }
}
