gggg

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;



int main()
{
   int n,k, r = 0;
    cin>>n;
    vector<int> d(n+1);

    for(int i = 1;i<=n;i++)
    {
        cin>>d[i];

    }
    vector<int> b(n+1);
    b[1] = d[1];
    b[2] = d[2] - d[1];
    for(int i = 3;i<=n;i++)
    {
        long a =   max( d[i] , d[i-1] )  - min ( d[i] , d[i-1] );
        long z = 3 *  (max ( d[i] , d[i-2] )  - min ( d[i] , d[i-2] ) );
        b[i] = min(a,z) + b[i-2];



    }
    cout<<b[n]<<endl;
}