n = int(input())
mx = [[0] for i in range(n + 1)] for j in range(n + 1)
for i in range(n):
    a = list(map(int, input().split()))
    for j in range(i + 1, n + 1):
        mx[i][j] = a[j - i - 1]
        mx[j][i] = a[j - i - 1]
w = [0] * (n + 1)
for i in range(1, n + 1):
    w[i] = mx[0][i]
    for j in range(1, i):
        w[i] = max(w[i], w[j] + mx[j][i])
print(w[n])