#include <iostream>
#include <vector>

using namespace std;

int main()
{
    int N;
    cin >> N;
    vector<int> A(N+3);
    vector<int> B(N+3);
    vector<int> C(N+3);
    vector<int> Sum(N+3);
    A[0] = A[1] = A[2] = B[0] = B[1] = B[2] = C[0] = C[1] = C[2] = 9999999999999;
    Sum[0] = Sum[1] = Sum[2] = 0;
    for (int i = 3; i < N + 3; ++i)
    {
        cin >> A[i] >> B[i] >> C[i];
        Sum[i] = min(min(Sum[i-2] + B[i-1], Sum[i-3] + C[i-2]), Sum[i-1] + A[i]);
    }
    cout << Sum[N+2];
    return 0;
}