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.*;


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();
		sc.close();
		int t[] = new int[n];
		
		int max = 0;
		for(int i=0;i<n;i++) max = Math.max(h[i], max);
		
		int cnt = 0;
		for(int i=0;i<max;i++) {

			boolean minus = false;
			for(int j=0;j<n;j++) {
				if(t[j]<h[j]) {
					if(!minus) {
						cnt++;
					}
					minus = true;
					t[j]++;
				}
				else {
					minus = false;
				}
			}
			
		}
		System.out.println(cnt);
		
	}
	

}
