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 count = 0;
        boolean flag = false;
        int sum = Arrays.stream(h).sum();

        while (sum != 0) {
            for (int i = 0; i < n; i++) {
                if (h[i] > 0) {
                    if (!flag) {
                        flag = true;
                        count++;
                    }
                    h[i]--;
                    sum--;
                } else {
                    flag = false;
                }
            }
            flag = false;
        }

        System.out.print(count);
    }
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz