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);
		int N = sc.nextInt();
		int h[] = new int[N];
		int max = 0;
		for(int i = 0; i < N; i++) {
			h[i] = sc.nextInt();
		}
		
		int h2[] = new int[N];
		int cnt = 0;
		boolean flag = true;
		while(flag) {
		flag = false;
		out : for(int i = 0; i < N; i++) {
			in : for(int j = i; j < N; j++) {
				if(h2[j] < h[j]) {
					flag = true;
					h2[j]++;
					//System.out.println("j" + j + ", h2:" + h2[j]);
				} else {
					if(i == j) {
						if(i == N - 1 && j == N - 1) {
							break out;
						}
						continue out;
					} else {
						//System.out.println(i + "," + j);
						break in;
					}
				}
			}
		//System.out.println(i);
			cnt++;
			i--;
		}
		}
		System.out.println(cnt);
	}
}
