#include <iostream>
#include <utility>
 
using namespace std;
 
const int R = 0;
const int G = 1;
const int B = 2;
const int M_H = 1000;
 
//작은 수를 반환하는 함수
inline int smaller(int a , int b)
{
	return a<b ? a : b;
}
inline int smaller(int a , int b , int c)
{//a가 가장 작? 참-> return a //거짓-> b가 가장 작냐? return b 아님 return c
	return (a<b&&a<c)? a : ((b<a&&b<c)? b : c);
}
 
int main() {
	int h[M_H][3];
	int h_num; //집 수
	scanf(" %d", &h_num);
 
	for(int i = 0 ; i < h_num ; i++) 
		scanf("%d %d %d\n",&h[i][R],&h[i][G],&h[i][B]);
 
    int memo[M_H][3]; //
	memo[0][R] = h[0][R]; memo[0][G] = h[0][G]; memo[0][B] = h[0][B]; 
 
	for(int i = 1 ; i < h_num ; i++)
	{
		memo[i][R] = smaller(memo[i-1][G]+h[i][R] , memo[i-1][B]+h[i][R]);
		memo[i][G] = smaller(memo[i-1][R]+h[i][G] , memo[i-1][B]+h[i][G]);
		memo[i][B] = smaller(memo[i-1][R]+h[i][B] , memo[i-1][G]+h[i][B]);
	}
 
	int answer = smaller(memo[h_num-1][R],memo[h_num-1][G],memo[h_num-1][B]);
 
    printf("%d",answer);
	return 0;
}

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