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
def reduce(x):
	return x-1
def sum(lst):
	cnt = 0
	for i in range(0, len(lst)):
		cnt += lst[i]
	return cnt
def calc(lst):
	if lst == []: return 0
	elif 0 in lst:
		lstlst = []
		newlst = []
		for i in range(0, len(lst)):
			if lst[i] == 0:
				lstlst.append(newlst)
				newlst = []
			else:
				newlst.append(lst[i])
		lstlst.append(newlst)
		return sum(map(calc, lstlst))
	else: return 1 + calc(map(reduce, lst))
	
N = int(raw_input())
h = map(int, raw_input().split())

print calc(h)