import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int K = sc.nextInt();
    int h[] = new int[K+1];
    int landCt =0;
    int answer=0;
    h[0]=0;
    for(int i=1;i<=K;i++){
      h[i] = sc.nextInt();
    }
    for(int i=0;i<101;i++){
      landCt=0;
      for(int j=0;j<K;j++){
        if(h[j]==0&&h[j+1]>0){
          landCt=landCt+1;
        }
      }
      answer = answer + landCt;
      oneMinus(h);
    }
      System.out.println(answer);   
  }
  
  public static void oneMinus(int[] h){
    for(int i=0;i<h.length;i++){
      if(h[i]!=0){
        h[i]=h[i]-1;
      }
    }
  }
  
}
/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