import java.util.*;

class Main{
  public static void main(String[] args){
    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 ans = H[0] + H[N-1];
    for(int i=1; i<N; i++)
      ans += Math.abs(H[i-1]-H[i]);
    System.out.println(ans/2);
  }
}
/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