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) {
		try(Scanner scan = new Scanner(System.in)){
			
			int N = scan.nextInt();
			int []h = new int[N];
			int hmax = 0;
			
			for(int i = 0;i<N;i++) {
				h[i] = scan.nextInt();
				if(hmax<h[i]) hmax = h[i];
			}
			int count = 0;
			while(true) {
			
			boolean katamari = false;
			
			
				for(int i = 0;i<N;i++) {
					
					if(h[i]!=0) katamari = true;
					
					if(katamari==true&&(h[i]==0||i==N-1)){
						count++;
						katamari = false;
					}
					
					if(h[i]!=0)h[i]--;
				}
				
				int zerocount = 0;
				for(int i = 0;i<N;i++) {
					if(h[i]==0)zerocount++;
					//System.out.print(h[i]);
					//System.out.print(" ");
					
				}
				//System.out.println();
				
				if(zerocount==N)break;
			}
			
			System.out.println(count);
			
			
		}
		
		
	}
		

}
