N = int(input())

table = [[0, 0, 0] for _ in range(N+1)]
for i in range(1, N+1):
  A = list(map(int, input().split()))
  for pre in range(3):
    for now in range(3):
      if pre == now: continue
      table[i][now] = max(table[i][now], max(table[i-1][pre]-1, 0)+A[now])

table1 = [[0, 0, 0] for _ in range(N+1)]
for i in range(1, N+1):
  for pre in range(3):
    for now in range(3):
      if pre == now: continue
      table1[i][now] = max(table1[i][now], table1[i-1][pre]+table[i][now])

print(max(table1[N]))