Problem:
Score : 300 points

Problem Statement

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.

Sample Input 1

4
1 2 2 1

Sample Output 1

2

The minimum number of watering operations required is 2.
One way to achieve it is:

Perform the operation with (l,r)=(1,3).

Perform the operation with (l,r)=(2,4).

Sample Input 2

5
3 1 2 3 1

Sample Output 2

5

Sample Input 3

8
4 23 75 0 23 96 50 100

Sample Output 3

221

Solution in Python (3.8.2) (judge verdict: Accepted)

# -*- coding: utf-8 -*-
import sys
from collections import deque, defaultdict
from math import sqrt, factorial, gcd
# def input(): return sys.stdin.readline()[:-1] # warning not \n
# def input(): return sys.stdin.buffer.readline().strip() # warning bytes
# def input(): return sys.stdin.buffer.readline().decode('utf-8')


def solve():
    n = int(input())
    a = [int(x) for x in input().split()]
    m = max(a)
    ans = 0
    for _ in range(m):
        b = a[:]
        for i in range(n):
            if a[i]:
                if i == 0 or a[i-1] == 0:
                    ans += 1
                b[i] -= 1
        a = b[:]

    print(ans)
        

t = 1
# t = int(input())
for case in range(1,t+1):
    ans = solve()


"""



"""