N = int(input())
A = [0]+[list(map(int,input().split())) for _ in range(N)]
dp = [[0 for _ in range(3)] for _ in range(N+1)]
f = [[0 for _ in range(3)] for _ in range(N+1)]
for j in range(3):
    dp[1][j] = A[1][j]
    f[1][j] = A[1][j]
for i in range(2,N+1):
    for j in range(3):
        s1 = dp[i-1][(j+1)%3]+max(0,f[i-1][(j+1)%3]-1)+A[i][j]
        s2 = dp[i-1][(j+2)%3]+max(0,f[i-1][(j+2)%3]-1)+A[i][j]
        if s1>=s2:
            dp[i][j] = s1
            f[i][j] = max(0,f[i-1][(j+1)%3]-1)+A[i][j]
        else:
            dp[i][j] = s2
            f[i][j] = max(0,f[i-1][(j+2)%3]-1)+A[i][j]
print(max(dp[N]))