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 PyPy3 (7.3.0) (judge verdict: Wrong Answer)

# import sys
# input = sys.stdin.readline
# import re
import collections
import bisect
import math
import fractions
import collections
import itertools
from functools import reduce

def main():
    n = int(input())
    h = list(input_list())
    count = 0
    while True:
        if len(set(h)) == 1:
            break
        flag = False
        count += 1
        for i, v in enumerate(h):
            if v != 0:
                flag = True
                h[i] -= 1
            else:
                if flag:
                    break
    print(count)

def minus(numbers):
    for i, n in enumerate(numbers):
        if n == 0:
            break
        numbers[i] -= 1
    return numbers


def input_list():
    return list(map(int, input().split()))


def input_list_str():
    return list(map(str, input().split()))


if __name__ == '__main__':
    main()