/*
A задание

#include <iostream>
#include <cmath>
#include <conio.h>

using namespace std;

int main() {
setlocale(LC_ALL, "Russian");

int N, P[10000], result = 2001, k = 4, max = 0, min = 2000000000, i, j;

cin >> N;

for (i = 0; i < N; i++)
{
cin >> P[i];
}

for (i = 0; i < (N - k); i++)
{
for (j = (i + k); j < N; j++)
{
if (P[i] + P[j] < result)
{
result = P[j] + P[i];
}
}
}
if (result == 2001)
{
result = -1;
}
cout << result;

_getch();
return 0;
}
*/
#include <iostream>
#include <cmath>
#include <conio.h>

using namespace std;

int main() {
    setlocale(LC_ALL, "Russian");

    int N, s = 4, result = 2001, i, P[10000], min = 1001, a;

    cin >> N;

    for (i = 0; i < s; i++)
    {
        cin >> a;
        P[i%s] = a;
    }
    for (i = s; i < N; i++)
    {
        cin >> a;
        if (P[i%s] < min)
        {
            min = P[i%s];
        }
        if (a + min < result)
        {
            P[i%s] = a;
            result = a + min;
        }
    }


    cout << result;

    _getch();
    return 0;
}