#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vii> vvii;
typedef vector<vi> vvi;
typedef pair<double, double> dodo;
#define pb(x) push_back(x)
#define mp(x, y) make_pair(x, y)
int N, M;
int input[3000][3000];
int mat[3000][3000];
int solve() {
for (int i = 0; i < N; i++) {
for (int j = 0; j < M; j++) {
mat[i][j] = input[i][j] - (i+j);
}
}
for (int i = N-2; i >= 0; i--) mat[i][M-1] = max(mat[i][M-1], mat[i+1][M-1]);
for (int j = M-2; j >= 0; j--) mat[N-1][j] = max(mat[N-1][j], mat[N-1][j+1]);
for (int i = N-2; i >= 0; i--) {
for (int j = M-2; j >= 0; j--) {
mat[i][j] = max( mat[i][j], max(mat[i+1][j], mat[i][j+1]) );
}
}
int ret = -1;
for (int i = 0; i < N; i++) {
for (int j = 0; j < M; j++) {
ret = max(ret, mat[i][j] - input[i][j] + (i+j) - 1);
}
}
return ret;
}
int main(int argc, char **argv) {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> N >> M;
for (int i = 0; i < N; i++) {
for (int j = 0; j < M; j++) {
cin >> input[i][j];
}
}
int ans = solve();
for (int i = 0; i < N/2; i++) {
for (int j = 0; j < M; j++) {
swap(input[i][j], input[N-1-i][j]);
}
}
ans = max(ans, solve());
for (int i = 0; i < N; i++) {
for (int j = 0; j < M; j++) {
input[i][j] = -input[i][j];
}
}
ans = max(ans, solve());
for (int i = 0; i < N/2; i++) {
for (int j = 0; j < M; j++) {
swap(input[i][j], input[N-1-i][j]);
}
}
ans = max(ans, solve());
cout << ans << endl;
return 0;
}
