package backjoon;

// https://www.acmicpc.net/problem/1149

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.util.StringTokenizer;

public class _1149 {

final static int Red = 0;

final static int Green = 1;

final static int Blue = 2;

static int[][] Cost;

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

// memory 12036 runtime 92

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

int N = Integer.parseInt(br.readLine());

Cost = new int[N][3];

StringTokenizer st;

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());

}

// 모든 경우의 수 중 최솟값을 더하기

for (int i = 1; i < N; i++) {

Cost[i][Red] += Math.min(Cost[i - 1][Green], Cost[i - 1][Blue]);

Cost[i][Green] += Math.min(Cost[i - 1][Red], Cost[i - 1][Blue]);

Cost[i][Blue] += Math.min(Cost[i - 1][Red], Cost[i - 1][Green]);

}

System.out.println(Math.min(Math.min(Cost[N - 1][Red], Cost[N - 1][Green]), Cost[N - 1][Blue]));

}

}

/*

input

3

26 40 83

49 60 57

13 89 99

output

96

*/