#include <iostream>

using namespace std;

int cost[1000006];
int n;
int ans[1000006];

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

    ans[n - 1] = cost[n - 1];
    ans[n - 2] = cost[n - 2];
    for(int i = n - 3; i > 0; i--)
    {
        ans[i] = cost[i] + min(ans[i + 1], ans[i + 2]);
    }

    int curBest = cost[n] + min(ans[1], ans[2]);

    ans[n] = cost[n];
    ans[n - 1] = cost[n - 1];
    for(int i = n - 2; i > 0; i--)
    {
        ans[i] = cost[i] + min(ans[i + 1], ans[i + 2]);
    }

    curBest = min(curBest, ans[1]);

    cout << curBest;
}