import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Back_1149 {

    final static int red = 0;
    final static int green = 1;
    final static int blue = 2;

    static int[][] cost;
    static int[][] dp;


    public static void main(String[] args) throws IOException {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st;
        int N = Integer.parseInt(br.readLine());

        cost = new int[N][3];
        dp = new int[N][3];

        for (int i = 0; i < N; i++) {
            st = new StringTokenizer(br.readLine());
            cost[i][red] = Integer.parseInt(st.nextToken());
            cost[i][green] = Integer.parseInt(st.nextToken());
            cost[i][blue] = Integer.parseInt(st.nextToken());
        }

        dp[0][red] = cost[0][red];
        dp[0][green] = cost[0][green];
        dp[0][blue] = cost[0][blue];

        System.out.println(Math.min(color_cost(N - 1, red), Math.min(color_cost(N - 1, green), color_cost(N - 1, blue))));
        br.close();
    }

    private static int color_cost(int N, int color) {

        if (dp[N][color] == 0) {
            if(color == red){
                dp[N][red] = Math.min(color_cost(N-1,green),color_cost(N-1,blue)) + cost[N][red];
            }
            else if(color == green){
                dp[N][green] = Math.min(color_cost(N-1,red),color_cost(N-1,blue)) + cost[N][green];
            }
            else{
                dp[N][blue] = Math.min(color_cost(N-1,red),color_cost(N-1,green)) + cost[N][blue];
            }
        }

        return dp[N][color];
    }
}