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 answer = 0;
		for(int i = 0; i < n; i++) {
			while(h[i] != 0) {
				answer += 1;
				for(int j = i; j < n; j++) {
					if(h[j] <= 0)
						break;
					else
						h[j] -= 1;
				}
			}
		}
		System.out.println(answer);
	}

}
/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