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.*;

class Main{
  public static void main(String args[]){
	Scanner sc= new Scanner(System.in);
	int n = sc.nextInt();
	int[] h = new int[n+2];
	int answer = 0;
	for(int i = 1; i <= n; i++){
	  h[i] = sc.nextInt();
	}
	int flag = 0;
	int flag2 = 0;
	int count = 0;
	int hoge = 0;
	int i = 1;
	while(flag == 0){
	  while(h[i]!=0 && i <= n){
	  	hoge = h[i];
		h[i]--;
		i++;
		flag2++;
	  }
	  if(i == n+1 && flag2 == 0){
		 flag++;
	  }else if(i == n+1){
	  	flag2 = 0;
		i = 1;
		if(hoge != 0){
			answer++;
		}
		hoge = 0;
	  }else if(hoge != 0){
	  	answer++;
		i++;
		hoge = 0;
	  }else{
	  	i++;
		hoge = 0;
	  }
	}
	System.out.print(answer);
  }
}
