import java.util.*;

public class _1149 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());
        int[] RGB = Arrays.stream(sc.nextLine().split(" ")).mapToInt(Integer::parseInt).toArray();
        int dpR = RGB[0], dpG = RGB[1], dpB = RGB[2];
        int prevR = dpR, prevG = dpG, prevB = dpB; 
        for(int i=1; i<N; i++) {
            RGB = Arrays.stream(sc.nextLine().split(" ")).mapToInt(Integer::parseInt).toArray();
            dpR = RGB[0] + Math.min(prevG, prevB);
            dpG = RGB[1] + Math.min(prevR, prevB);
            dpB = RGB[2] + Math.min(prevG, prevR);
            
            prevR = dpR; prevG = dpG; prevB = dpB; 
        }
        sc.close();

        System.out.println(Math.min(dpR,Math.min(dpG, dpB)));
    }
}