n = int(input())
arr = []
for i in range(n):
    temp = list(map(int,input().split()))
    arr.append(temp)
for i in range(1,n):
    for j in range(n):
        arr[i][j] += arr[i-1][j]
dp = [0] *150
f = [0] *150
ans = 0
for i in range(n):
    for k in range(i+1):
        for j in range(n):
            f[j] = arr[i][j] - arr[i-k][j]
            dp[j] = max(dp[j-1]+f[j],f[j])
            ans = max(ans,dp[j])
print(ans)