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];
		int max = 0;
		for (int i = 0; i < n; i++) {
			h[i] = sc.nextInt();
			max = Math.max(max,h[i]);
		}
		int count = 0;
		int ans = 0;
		for (int i = 1; i <= max; i++) {
			count = 0;
			for (int j = 0; j < n; j++) {
				if(h[j]>0) {
					if(j==0) count++;
					else if(h[j-1] == 0) count++;
				}
			}
			for (int j = 0; j < n; j++) {
				if(h[j]>0) h[j]-=1;
			}
			ans += count;
		}
		System.out.println(ans);
		sc.close();
	}
}
/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