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 {

	static int flower[] = new int[100];
	static int flower_h[] = new int[100];
	
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int num = sc.nextInt();
		int count = 0;
		
		for(int i = 0; i < num; i++) {
			flower_h[i] = sc.nextInt();
		}
		
		if(num == 1) {
			System.out.println(flower_h[0]);
			return;
		}
	
		while(!isHeight(num)) {
			for(int i = 0; i < num; i++) {
				
				//現在の花の高さが既に同じの場合はスキップ
				if(flower_h[i] == flower[i]) { 
					continue;
				}
				
				//水やり
				flower[i]++;
				
				//右端の場合はbreak
				if(i == num -1 ) {
					break;
				}
				
				//右隣の高さが同じの場合はbreak;
				if(flower_h[i+1] == flower[i+1]) {
					break;
				}
			}
			count++;
		}
		
		System.out.println(count);

	}
	
	public static boolean isHeight(int len) {
		
		for(int i = 0; i < len; i++) {
			if(flower_h[i] != flower[i]) {
				return false;
			}
		}
		return true;
	}
}

