#include <fstream>
#include <iostream>
using namespace std;
int myMax(int a, int b)
{
return (a > b ? a : b);
}
int myMax(int a, int b, int c)
{
return myMax(myMax(a, b), c);
}
const int NMAX = 1000;
const int INF = 2e9;
int n, m;
int a[NMAX + 1][NMAX + 1];
int dp[4][NMAX + 1][NMAX + 1];
int ans = -1;
void solve()
{
cin >> n >> m;
for(int i = 1; i <= n; i++)
for(int j = 1; j <= m; j++)
cin >> a[i][j];
for(int k = 0; k <= 3; k++)
{
for(int i = 0; i <= n + 1; i++)
dp[k][i][0] = dp[k][i][m + 1] = -INF;
for(int j = 1; j <= m; j++)
dp[k][0][j] = dp[k][n + 1][j] = -INF;
}
for(int i = 1; i <= n; i++)
for(int j = 1; j <= m; j++)
dp[0][i][j] = myMax(dp[0][i][j - 1], dp[0][i - 1][j], -a[i][j]) - 1;
for(int i = 1; i <= n; i++)
for(int j = m; j >= 1; j--)
dp[1][i][j] = myMax(dp[1][i][j + 1], dp[1][i - 1][j], -a[i][j]) - 1;
for(int i = n; i >= 1; i--)
for(int j = 1; j <= m; j++)
dp[2][i][j] = myMax(dp[2][i][j - 1], dp[2][i + 1][j], -a[i][j]) - 1;
for(int i = n; i >= 1; i--)
for(int j = m; j >= 1; j--)
dp[3][i][j] = myMax(dp[3][i][j + 1], dp[3][i + 1][j], -a[i][j]) - 1;
for(int i = 1; i <= n; i++)
for(int j = 1; j <= m; j++)
if(a[i][j] + myMax(myMax(dp[0][i][j], dp[1][i][j], dp[2][i][j]), dp[3][i][j]) > ans)
ans = a[i][j] + myMax(myMax(dp[0][i][j], dp[1][i][j], dp[2][i][j]), dp[3][i][j]);
cout << ans << '\n';
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
