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.*;
class Main {
    public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);
	int N = sc.nextInt();
	int[] h = new int[N];
	int hMax = 0;
	for(int i = 0; i<N; i++) {
	    h[i] = sc.nextInt();
	    hMax = Math.max(h[i], hMax);
	}

	int height = 0;
	int shima = 0;
	for(int k = 0; k<hMax; k++) {
	    boolean isConnect = false;
	    for(int i = 0; i<N; i++) {
		if(h[i]-height > 0 ) {
		    if(isConnect == false) shima++;
		    isConnect = true;
		}else {
		    isConnect = false;
		}
	    }
	    height++;
	}
	System.out.println(shima);
    }
}