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[]){

        // スキャナーの宣言
        Scanner sc = new Scanner(System.in);
        // 整数の入力
		int n = sc.nextInt();
        //配列の宣言
        int[] h = new int[n];

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

        int l = 0, j, min, answer = 0;
        while(l < n){
            while(l < n && h[l] == 0){
                l++;
            }
            if(l == n) break;
            j = l;
            min = h[l];
            while(j < n && h[j] != 0){
                min = Math.min(h[j], min);
                j++;
            }
            for(int k = 0; k < j; k++){
                h[k] -= min;
            }
            answer += min;
        }

        // 出力
        System.out.println(answer);

    }

}