// islands.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
#include <vector>
#include <cmath>
using namespace std;
int n;
vector<int>dp;
int main()
{
    cin >> n;
    dp.resize(n);
    for (int i = 0; i < n; i++) {
        cin >> dp[i];
    }
    dp[1] += dp[0];
    for (int i = 2; i < n; i++) {
        dp[i] += min(dp[i - 1], dp[i - 2]);
    }
    cout << dp[n - 1];
}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

// Tips for Getting Started: 
//   1. Use the Solution Explorer window to add/manage files
//   2. Use the Team Explorer window to connect to source control
//   3. Use the Output window to see build output and other messages
//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file