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 x[]=new int[N];
		int y[]=new int[N];
		for(int i=0;i<N;i++) {
			x[i]=sc.nextInt();
			y[i]=x[i];
		}
		int sum=0;

		for(int i=0;i<N;i++) {
			if(i!=N-1) {
				if(y[i]<=x[i+1]) {
					y[i]=0;
				}
			}
			if(i!=0) {
				if(y[i]<x[i-1]) {
					y[i]=0;
				}
			}
			sum+=y[i];
		}
		Boolean j=false;
		int min=0;
		for(int i=0;i<N;i++) {
			if(y[i]!=0) {
				j=true;
			}
			if(j) {
				if(y[i]==0) {
					if(min>x[i]) {
						min=x[i];
					}
				}else {
					sum-=min;
					min=101;
				}
			}
		}
		System.out.println(sum);
	}
}