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];
        for (int i = 0; i < h.length; i++) {
            h[i] = sc.nextInt();
        }
        int ans = 0;
        while(true) {
            boolean flg = false;
            for (int i = 0; i < n; i++) {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            }
            if(!flg) {
                break;
            }
            ans++;
        }
        System.out.println(ans);
    }
}
/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