#include <bits/stdc++.h>
using namespace std;
#define int              long long int
#define double           long double
#define print(a)         for(auto x : a) cout << x << " "; cout << endl


const int M = 1000000007;
const int N = 3e5+9;
const int INF = 2e9+1;
const int LINF = 2000000000000000001;

inline int power(int a, int b, int mod=M) {
    int x = 1;
    a %= mod;
    while (b) {
        if (b & 1) x = (x * a) % mod; 
        a = (a * a) % mod;
        b >>= 1;
    }
    return x;
}


//_ ***************************** START Below *******************************




vector<vector<int>> a;

int consistency(int n){
	
    vector<vector<vector<int>>> dp(n/2, vector<vector<int>>(3, vector<int>(3, INF))); 
    
    for(int i=0; i<=n/2-1; i++){    
    	
        for(int j=0; j<3; j++){
            for(int k=0; k<3; k++){
                if(j==k) continue;  
                
                dp[i][j][k] = a[i][j] + a[n-i-1][k];    
                if(i==0) continue;
                
                int mini = INF;
                for(int p=0; p<3; p++){
                    for(int q=0; q<3; q++){
                        if(p==q || p==j || q==k) continue;
                        mini = min(mini,  dp[i-1][p][q]);
                    }
                }
                dp[i][j][k] += mini;
            }
        }
    }  
    
    int mini = INF;
    for(int i=0; i<3; i++){
        for(int j=0; j<3; j++){
            mini = min(mini, dp[n/2-1][i][j]);
        }
    }

    return mini;

}















int practice(int n){


    return 0;
}





void solve() {
    
    int n;
    cin>> n;
    
    a.resize(n);
    for(int i=0; i<n; i++){
    	int x, y, z;
    	cin >> x >> y >> z;
    	a[i] = {x, y, z};
    }
    
    cout << consistency(n) << endl;


}





int32_t main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }

    return 0;
}