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 C++14 (GCC 5.4.1) (judge verdict: Accepted)


#include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <map>
#include <stdio.h>
using namespace std;

//typedefリスト
typedef vector<int> vint;
typedef vector<string> vstr;

int main(void) {
	int N, jur, cou,ans,num;
	num=0;
	ans = 0;
	cou = 0;
	cin >> N;
	vint h(N);
	vint H(N);
	for (int i = 0; i < N; ++i) {
		cin >> h[i];
		H[i] = 0;
	}


	for (int j = 0;num==0; ++j) {
		jur = 0;
		cou = 0;
		num = 0;
		for (int i = 0; i < N; i++) {
			if (H[i] == h[i])jur++;
		}
		if (jur == N) {
			ans = j;
			num = 1;
		}

		for (int i = 0; i < N; ++i) {
			if (H[i] != h[i]) {
				++H[i];
				++cou;
			}
			else if (cou != 0)break;

		}
		
	}
	cout << ans << endl;
}