import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
      	int[] arrs = new int[n + 1];
      	for (int i = 1; i <= n; i++) {
        	arrs[i] = sc.nextInt();
        }
		int result = 0;
      	for (int i = 1; i <= n; i++) {
        	result += Math.max(arrs[i] - arrs[i - 1], 0);
        }
      	System.out.println(result);
    }
}
/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