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+1];
		for (int i = 1; i <= n; i++) {
			h[i] = sc.nextInt();
		}
h[0]=0;
int ans=0;
for (int i =0; i <= n-1; i++) {
if(h[i]<h[i+1]){
ans+=h[i+1]-h[i];
}
}
System.out.println(ans);
	}
}
/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