import java.util.*;
public 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 count = 0;
    int start = 0;
    while(start < n){
      if(h[start]==0){
        start++;
        continue;
      }
      count++;
      h[start]--;
      for(int i = start+1;i<n;i++){
        if(h[i]==0){
          break;
        }
        h[i]--;
      }
    }
    System.out.println(count);
  }
} import java.util.*; util.* java public 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 count = 0;
    int start = 0;
    while(start < n){
      if(h[start]==0){
        start++;
        continue;
      }
      count++;
      h[start]--;
      for(int i = start+1;i<n;i++){
        if(h[i]==0){
          break;
        }
        h[i]--;
      }
    }
    System.out.println(count);
  }
} 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 count = 0;
    int start = 0;
    while(start < n){
      if(h[start]==0){
        start++;
        continue;
      }
      count++;
      h[start]--;
      for(int i = start+1;i<n;i++){
        if(h[i]==0){
          break;
        }
        h[i]--;
      }
    }
    System.out.println(count);
  } main {
    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 count = 0;
    int start = 0;
    while(start < n){
      if(h[start]==0){
        start++;
        continue;
      }
      count++;
      h[start]--;
      for(int i = start+1;i<n;i++){
        if(h[i]==0){
          break;
        }
        h[i]--;
      }
    }
    System.out.println(count);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int[] h = new int[n]; h new int[n] n for(int i = 0;i<n;i++){
      h[i] = sc.nextInt();
    } int i = 0; int i = 0; i 0 i<n i n i++ i++ i {
      h[i] = sc.nextInt();
    } {
      h[i] = sc.nextInt();
    } h[i] = sc.nextInt() h[i] h i sc.nextInt() sc.nextInt sc int count = 0; count 0 int start = 0; start 0 while(start < n){
      if(h[start]==0){
        start++;
        continue;
      }
      count++;
      h[start]--;
      for(int i = start+1;i<n;i++){
        if(h[i]==0){
          break;
        }
        h[i]--;
      }
    } start < n start n {
      if(h[start]==0){
        start++;
        continue;
      }
      count++;
      h[start]--;
      for(int i = start+1;i<n;i++){
        if(h[i]==0){
          break;
        }
        h[i]--;
      }
    } if(h[start]==0){
        start++;
        continue;
      } h[start]==0 h[start] h start 0 {
        start++;
        continue;
      } start++ start continue; count++ count h[start]-- h[start] h start for(int i = start+1;i<n;i++){
        if(h[i]==0){
          break;
        }
        h[i]--;
      } int i = start+1; int i = start+1; i start+1 start 1 i<n i n i++ i++ i {
        if(h[i]==0){
          break;
        }
        h[i]--;
      } {
        if(h[i]==0){
          break;
        }
        h[i]--;
      } if(h[i]==0){
          break;
        } h[i]==0 h[i] h i 0 {
          break;
        } break; h[i]-- h[i] h i System.out.println(count) System.out.println System.out System System.out count String[] args args public 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 count = 0;
    int start = 0;
    while(start < n){
      if(h[start]==0){
        start++;
        continue;
      }
      count++;
      h[start]--;
      for(int i = start+1;i<n;i++){
        if(h[i]==0){
          break;
        }
        h[i]--;
      }
    }
    System.out.println(count);
  }
} public 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 count = 0;
    int start = 0;
    while(start < n){
      if(h[start]==0){
        start++;
        continue;
      }
      count++;
      h[start]--;
      for(int i = start+1;i<n;i++){
        if(h[i]==0){
          break;
        }
        h[i]--;
      }
    }
    System.out.println(count);
  }
} Main
import java.util.*;
public 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 count = 0;
    int start = 0;
    while(start < n){
      if(h[start]==0){
        start++;
        continue;
      }
      count++;
      h[start]--;
      for(int i = start+1;i<n;i++){
        if(h[i]==0){
          break;
        }
        h[i]--;
      }
    }
    System.out.println(count);
  }
}
