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 scan = new Scanner(System.in);
		int ans=0;
		int a=scan.nextInt();
		int b[]=new int[a];
		for(int i=0;i!=a;i++) {
			b[i]=scan.nextInt();
		}
		int i=0;
		int k=0;
		for(int o=0;;o++) {
			if(o==a) {
				k=1;
				break;
		}
		if(b[o]!=0) {
			break;
		}
		}
		if(k==1) {
			System.out.println(0);
		}
		else {
			k=0;
		for(;;) {
			if(k==1) {
				break;
			}
			if(b[i]!=0) {
				for(int j=i;;j++) {
					if(j==a) {
						break;
					}
					if(b[j]==0) {
						break;
					}
					b[j]--;
				}
				ans++;
				i=0;
				for(int j=0;j!=a+1;j++) {
					if(j==a) {
						k=1;
						break;
				}
				if(b[j]!=0) {
					break;
				}
					
				}
				continue;
			}
			
			i++;
		}
		System.out.println(ans);
	}
		}
	}