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 a(l):
  if len(l) == 0:
    return 0
  elif len(l) == 1:
    return l[0]
  else:
    m = min(l)
    for j in range(len(l)):
      if m == l[j]:
        return l[j] + a(map(lambda x: x-m,l[0:j])) + a(map(lambda x: x-m,l[j+1:]))
        

i = int(input())
l = raw_input().split()
l = map(lambda x: int(x),l)

print a(l)