#include<stdio.h>
#define MAX_ARR_LEN 1000

int arr[MAX_ARR_LEN][3] = { 0 };
int result[MAX_ARR_LEN][3] = { 0 };

int min(int a, int b) {
	if (a < b)
		return a;
	else
		return b;
}
int main(void) {
	int N;
	scanf("%d", &N);

	for (int i = 0; i < N; i++) {
		for (int j = 0; j < 3; j++) {
			scanf("%d", &arr[i][j]);
		}
	}

	// 0: 빨강, 1: 초록, 2: 파랑
	result[0][0] = arr[0][0];
	result[0][1] = arr[0][1];
	result[0][2] = arr[0][2];

	for (int i = 1; i < N; i++) {
		result[i][0] = min(result[i - 1][1], result[i - 1][2]) + arr[i][0];
		result[i][1] = min(result[i - 1][0], result[i - 1][2]) + arr[i][1];
		result[i][2] = min(result[i - 1][0], result[i - 1][1]) + arr[i][2];
	}

	int minVal = 1000000;
	for (int i = 0; i < 3; i++)
		minVal = min(minVal, result[N - 1][i]);
	printf("%d", minVal);