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.Scanner;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int h[] = new int[N];
		int k[] = new int[N];
		boolean b[] = new boolean[N];
		int count = 0;
		for(int i = 0;i < N;i++) {
			k[i] = sc.nextInt();
		}
		int oc = 0;
		while(true) {
			int e = oc;
			for(int i = oc;i < N;i++) {
				for(int q = oc;q < N;q++) {
					oc=q;
					if(h[q] != k[q])break;
				}
				if(h[i] != k[i]) {
					e++;
				}
				if(h[i] == k[i]) {
					break;
				}
			}
			boolean w = false;
			for(int j = oc;j < e;j++) {
				if(h[j] != k[j]) {
					w = true;
					h[j]++;
				}
			}
			if(w)count++;

			//---
			boolean f = true;
			for(int i = 0;i < N;i++) {
				if(h[i] != k[i])f=false;
			}
			if(f)break;
		}

		System.out.println(count);
	}
}