MY code：

#include<iostream>
#include<cstdio>
using namespace std;
const long long N=1e5+5;
long long n,ans;
long long a[N];
int main() {
	cin>>n;
	for(int i=1; i<=n; i++) cin>>a[i];
	ans+=6+a[1]*6;
	for(int i=2; i<=n; i++) {
		if(a[i]>a[i-1]) {
			ans+=(a[i]-a[i-1])*6+6;
			continue; 
		} else if(a[i]==a[i-1]) {
			ans++;
			continue;
		} else {
			ans+=(a[i-1]-a[i])*4+6;
			continue;
		}
	}
	cout<<ans+a[n]*4-5<<endl;
	return 0;
}