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 {
	Scanner sc = new Scanner(System.in);

	static int cnt;
	void doIt() {
		int n = sc.nextInt();
		int[] h = new int[n];
		int min = 101;
		cnt = 0;
		for(int i = 0; i < n; i++) {
			h[i] = sc.nextInt();
			if(h[i] < min)min = h[i];
		}
		getAns(h, 0, n - 1, 0);
		System.out.println(cnt);
	}

	void getAns(int[] h, int l, int r, int d) {
		if(l > r)return;
		int min = 101, idx = -1;
		for(int i = l; i <= r; i++) {
			if(min > h[i]) {
				min = h[i];
				idx = i;
			}
		}
		cnt += min - d;
		if(min <= d)min = d;
		if(min - d == 0) d = 0;
		getAns(h, l, idx - 1, min);
		getAns(h, idx + 1, r, min);
	}
	public static void main(String[] args) {
		new Main().doIt();
	}
}
