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 sum=0;
    boolean flag=true;
    while(flag){
      flag=false;
      boolean ed=false;
      for(int i=0;i<n;i++){
        if(h[i]!=0){
          h[i]=h[i]-1;
          if(!ed){
            ed=true;
            flag=true;
            sum++;
          }
        }else{
          ed=false;
        }
      }
    }
    System.out.println(sum);
  }
}
/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