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

/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