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 <bits/stdc++.h>
using namespace std;
#define MD 1000000007
#define INF 1000000000
typedef long long int ll;
typedef pair<ll,ll> P;
template <typename T> std::string tostr(const T& t){std::ostringstream os; os<<t; return os.str();}
int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
 
int main(){
    int n;
    cin>>n;
    vector<int> v(n),v2(n,0);
    for(int i=0;i<n;i++){
        cin>>v[i];
    }
    int k=0;
    for(int j=0;j<n;j++){
            if(v2[j]==v[j]){
                k++;
            }
    }
     if(k==n){
        cout<<0<<endl;
        return 0;
    }
    ll ans=1;
    while(1){
        int cnt=0,flag=0;
        for(int j=0;j<n;j++){
            if(v2[j]==v[j]&&flag==1){
                break;
            }else if(v2[j]<v[j]){
                v2[j]++;
                flag=1;
            }
        }
        for(int j=0;j<n;j++){
            if(v2[j]==v[j]){
                cnt++;
            }
        }
        if(cnt==n){
            cout<<ans<<endl;
            break;
        }
        ans++;
    }

    return 0;
}