import java.util.*;
public class Main {

	static int flower[] = new int[100];
	static int flower_h[] = new int[100];
	
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int num = sc.nextInt();
		int count = 0;
		
		for(int i = 0; i < num; i++) {
			flower_h[i] = sc.nextInt();
		}
		
		if(num == 1) {
			System.out.println(flower_h[0]);
			return;
		}
	
		while(!isHeight(num)) {
			for(int i = 0; i < num; i++) {
				
				//現在の花の高さが既に同じの場合はスキップ
				if(flower_h[i] == flower[i]) { 
					continue;
				}
				
				//水やり
				flower[i]++;
				
				//右端の場合はbreak
				if(i == num -1 ) {
					break;
				}
				
				//右隣の高さが同じの場合はbreak;
				if(flower_h[i+1] == flower[i+1]) {
					break;
				}
			}
			count++;
		}
		
		System.out.println(count);

	}
	
	public static boolean isHeight(int len) {
		
		for(int i = 0; i < len; i++) {
			if(flower_h[i] != flower[i]) {
				return false;
			}
		}
		return true;
	}
}


/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