

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		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;;
		while(true){
			//0じゃないところを探す
			int start = -1;
			for(int i = 0; i < n; i++){
				if(h[i] != 0){
					start = i;
					break;
				}
			}

			if(start < 0){
				break;
			}

			count++;

			for(int i = start; i < n; i++){
				if(h[i] == 0){
					break;
				}

				h[i]--;
			}
		}

		System.out.println(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