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);
	// 整数の入力
	int n = sc.nextInt();

	int[] h = new int[n];
	for(int i = 0; i < n; i++){
	    h[i] = sc.nextInt();
	}

	int ans = 0;
	boolean lastWatered;
	for(int level = 100; level > 0; level--){
	    lastWatered = false;
	    for(int i = 0; i < n; i++){
		if(h[i] == level){
		    h[i]--;
		    if(lastWatered){
			// do nothing
		    }else{
			ans++;
			lastWatered = true;
		    }
		}else{
		    lastWatered = false;
		}
	    }
	}

	System.out.println(ans);
    }

}


