#define _CRT_SECURE_NO_WARNINGS
#define MIN(a,b) (a<b ? a:b)
#include <stdio.h>
#include <stdlib.h>
int main()
{
int n;
scanf("%d", &n);
int **house = (int **)calloc(n, sizeof(int));
for(int i=0; i<n; i++)
{
house[i] = (int *)calloc(3, sizeof(int));
for(int j=0; j<3; j++)
{
int color;
scanf("%d", &color);
house[i][j] = color;
}
}
int **dp = (int **)calloc(n, sizeof(int));
for(int i=0; i<3; i++)
{
dp[i] = (int *)calloc(3, sizeof(int));
}
dp[0] = house[0];
for(int i=1; i<n; i++)
{
dp[i][0] = MIN(dp[i-1][1] + house[i][0], dp[i-1][2] + house[i][0]);
dp[i][1] = MIN(dp[i-1][0] + house[i][1], dp[i-1][2] + house[i][1]);
dp[i][2] = MIN(dp[i-1][0] + house[i][2], dp[i-1][1] + house[i][2]);
}
printf("%d", MIN(dp[n-1][0], MIN(dp[n-1][1], dp[n-1][2])));
}