#include<bits/stdc++.h>
#define ll long long
#define vl vector<ll>
#define pb push_back
#define sz(v) (ll)(v.size())
#define f first
#define s second
#define pll pair<ll, ll>
using namespace std;
void solve()
{
ll n, m, i, j;
cin >> n >> m;
ll grid[n+1][m+1];
for(i = 1; i <= n; i++)
{
for(j = 1; j <= m; j++)
cin >> grid[i][j];
}
ll mx[n+1][m+1], mn[n+1][m+1];
for(i = 0; i <= n; i++)
{
for(j = 0; j <= m; j++)
{
mn[i][j] = 1000000000000;
mx[i][j] = -1000000000000;
}
}
ll rs = LLONG_MIN;
for(i = 1; i <= n; i++)
{
for(j = 1; j <= m; j++)
{
mn[i][j] = min(mn[i-1][j], mn[i][j-1]);
mx[i][j] = max(mx[i-1][j], mx[i][j-1]);
mn[i][j] = min(mn[i][j], grid[i][j]-i-j);
mx[i][j] = max(mx[i][j], grid[i][j]+i+j);
rs = max(rs, mx[i][j]-i-j-grid[i][j]-1);
rs = max(rs, grid[i][j]-i-j-mn[i][j]-1);
}
}
for(i = 1; i <= n; i++)
{
for(j = 1; j <= m / 2; j++)
swap(grid[i][j], grid[i][m-j+1]);
}
for(i = 1; i <= n; i++)
{
for(j = 1; j <= m; j++)
{
mn[i][j] = min(mn[i-1][j], mn[i][j-1]);
mx[i][j] = max(mx[i-1][j], mx[i][j-1]);
mn[i][j] = min(mn[i][j], grid[i][j]-i-j);
mx[i][j] = max(mx[i][j], grid[i][j]+i+j);
rs = max(rs, mx[i][j]-i-j-grid[i][j]-1);
rs = max(rs, grid[i][j]-i-j-mn[i][j]-1);
}
}
cout << rs << "\n";
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
ll tests = 1;
//cin >> tests;
while(tests--)
{
solve();
}
}
