題目十八

題目：Elevator

我的代碼：

```cpp
#include<iostream>
using namespace std;

int main(){
    int N,f = 0,s = 0,sum = 0;
    cin>>N;
    
    sum += N*5;
    for(int i = 0;i < N;i++){
        cin>>s;
        s - f > 0 ? sum += (s-f)*6 : sum += (f-s)*4;
        f = s;
    }
    cout<<sum;
    return 0;
}