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.Arrays;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		final Scanner sc = new Scanner(System.in);
		
		final int N = sc.nextInt();
		sc.nextLine();
		
		final int[] hs = new int[N];
		for (int i = 0; i < N; i++) {
			hs[i] = sc.nextInt();
		}
		
		int count = 0;
		while (true) {
			int l = -1;
			for (int i = 0; i < N; i++) {
				final int h = hs[i];
				if (h > 0) {
					if (l < 0) {
						l = i;
					}
				} else {
					if (l >= 0) {
						// supply water
						for (int j = l; j < i; j++) {
							hs[j] = hs[j] - 1;
						}
						count++;
					}
					
					l = -1;
				}
			}
			
			if (l >= 0) {
				// supply water
				for (int j = l; j < N; j++) {
					hs[j] = hs[j] - 1;
				}
				count++;
			}
			
			if (Arrays.stream(hs).allMatch(j -> j == 0)) {
				break;
			}
		}
		
		System.out.println(count);
	}

}