#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int,int> P;
#define REP(i,n) for(int i=0;i<int(n);i++)




ll dp[5010][4],dp1[5010][4];


int main(void){
	cin.tie(nullptr);  ios_base::sync_with_stdio(false);
	ll i,j;




	ll N;
	cin >> N;
	for(i=1;i<=N;i++){
		for(j=1;j<=3;j++){
			cin >> dp[i][j];
		}
	}


	for(i=1;i<=N;i++){
		dp[i][1]+=max(max(0LL,dp[i-1][2]-1),max(0LL,dp[i-1][3]-1));
		dp1[i][1]=dp[i][1]+max(dp1[i-1][2],dp1[i-1][3]);

		dp[i][2]+=max(max(0LL,dp[i-1][3]-1),max(0LL,dp[i-1][1]-1));
		dp1[i][2]=dp[i][2]+max(dp1[i-1][3],dp1[i-1][1]);

		dp[i][3]+=max(max(0LL,dp[i-1][1]-1),max(0LL,dp[i-1][2]-1));
		dp1[i][3]=dp[i][3]+max(dp1[i-1][1],dp1[i-1][2]);
	}



	ll ans=max(dp1[N][1],dp1[N][2]);
	ans=max(ans,dp1[N][3]);

	cout << ans << endl;





     return 0;

}