#include <iostream>
#define MAX 9999999
 
using namespace std;
 
int rgb[3][1000];
int last[3][1000];
int N;
int low = 9999999;
 
void solution(int deep, int check, int sum)
{
	if (deep == N)
	{
		if (low > sum)
			low = sum;
		return;
	}
 
	for (int i = 0; i < 3; i++)
	{
		if (check == i) continue;	//이전의 색과 동일하다면 다른 색 선택
		else if (last[i][deep] <= sum + rgb[i][deep]) continue;	// 같은 위치에 이전에 입력된 것이 더 작을 경우
		else last[i][deep] = sum + rgb[i][deep];
		solution(deep + 1, i, last[i][deep]);
	}
}
int main(void)
{
	cin >> N;
 
	for (int i = 0; i < N; i++)
	{
		for (int j = 0; j < 3; j++)
		{
			cin >> rgb[j][i];
			last[j][i] = MAX;
		}
	}
	solution(0, 3, 0);
	cout << low;
	return 0;
}

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