N = int(input())
A = [list(map(int, input().split())) for _ in range(N)]

INF = 10**18

dp = [[0]*3 for _ in range(N+1)]
power = [[-INF]*3 for _ in range(N+1)]
for i in range(3):
    power[0][i] = 0
for i in range(N):
    for j in range(3):
        for k in range(3):
            if j == k:
                continue
            if power[i+1][j] < max(power[i][k]+A[i][j]-1, 0):
                dp[i+1][j] = dp[i][k]+power[i][k]+A[i][j]
                power[i+1][j] = max(power[i][k]+A[i][j]-1, 0)

print(max(dp[-1]))