#include <iostream>
#include <vector>
using namespace std;

int dp[25][10][10];
int n;
int m[25][3];
int rec(int i, int prev_color, int first_color) {
    if(i == 0) {
        if(prev_color == first_color) {
            return m[0][prev_color];
        }
        return 100000;
    }

    if(dp[i][prev_color][first_color] != -1) {
//        return dp[i][prev_color][first_color];
    }
    int result = 100000;
    for(int j = 0; j < 3; j++) {
        if(prev_color != j) {
            result = min(result, rec(i - 1, j, first_color) + m[i][j]);
        }
    }
    dp[i][prev_color][first_color] = result;
    return result;
}
int main()
{
    cin>>n;
    for(int i=0; i<n; i++){
        for(int j=0; j<3; j++){
            cin>>m[i][j];
        }
    }
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < 3; j++) {
            for(int k = 0; k < 3; k++) {
                dp[i][j][k] = -1;
            }
        }
    }
    int result = 2e9;
    for(int i = 0; i < 3; i++) {

        for(int j = 0; j < 3; j++) {
            if(i != j) {
                result = min(result, rec(n - 1, i, j));
            }
        }
    }
    cout << result<< endl;
    return 0;
}