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) {
	    Scanner scanner = new Scanner(System.in);

	    int N = Integer.parseInt(scanner.next());
	    int[] H = new int[N];

	    
	    for (int i=0; i<N; i++) {
	    	H[i] = Integer.parseInt(scanner.next());
	    }

	    int c=0;
	    while(true) {
	    	boolean flg= false;
	    	for (int i=0; i<N; i++) {
		    	if (H[i] != 0) {
		    		H[i]--;
		    		flg=true;
		    	} else if(flg) {
		    		break;
		    	}
		    }
	    	if (!flg) {
	    		break;
	    	}
	    	c++;
	    }

	    System.out.println(c);
	}
}