In a flower bed, there are N flowers, numbered 1,2,......,N. Initially, the heights of all flowers are 0. You are given a sequence h=\\{h_1,h_2,h_3,......\\} as input. You would like to change the height of Flower k to h_k for all k (1 \leq k \leq N), by repeating the following "watering" operation:

* Specify integers l and r. Increase the height of Flower x by 1 for all x such that l \leq x \leq r.



Find the minimum number of watering operations required to satisfy the condition.

Constraints

* 1 \leq N \leq 100
* 0 \leq h_i \leq 100
* All values in input are integers.

Input

Input is given from Standard Input in the following format:


N
h_1 h_2 h_3 ...... h_N


Output

Print the minimum number of watering operations required to satisfy the condition.

Examples

Input

4
1 2 2 1


Output

2


Input

5
3 1 2 3 1


Output

5


Input

8
4 23 75 0 23 96 50 100


Output

221
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Random;
import java.util.Scanner;
public class Main {
	static Scanner sc = new Scanner(System.in);static void p(int i) {System.out.println(i);}static void p(long i) {System.out.println(i);}static void p(String i) {System.out.println(i);}static void p(double i) {System.out.println(i);}
	
	
	public static void main(String[] args) {
		int N=sc.nextInt();
		
		int h[]=new int[N];
		
		for(int i=0;i<N;i++) {
			h[i]=sc.nextInt();
		}
		
		int ans=0;
		
		for(int i=1;i<=100;i++) {
			
			for(int a=0;a<N;a++) {
				
				if(h[a]>=i) {
					while(h[a]>=i) {
						a++;
						if(a==N) {
							break;
						}
					}
					ans++;
					
				}
				
				
				
				
			}
			
			
		}
		p(ans);
	}
	
}
	
