#include <bits/stdc++.h>
typedef long long ll;
typedef long double ld;
using namespace std;
#define fi first
#define se second
#define sz(x) (x).size()
#define pll pair<ll,ll >
#define pb push_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define endln '\n'
#define cont continue
const ll MaxN = 1e3 + 100;
const ll LogN = 20;
ll Inf = 1e18;
const ll dx[4] = { 0,1,0,-1 };
const ll dy[4] = { 1,0,-1,0 };
bool used[MaxN][MaxN];
ll Mt[MaxN][MaxN];
ll dp[4][MaxN][MaxN];
int main() {
#ifdef LOCAL
ifstream cin("input.txt");
ofstream cout("output.txt");
#else
//ifstream cin("points.in");
//ofstream cout("points.out");
#endif
ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
ll N, M;
cin>>N>>M;
for(int i = 0;i<N;i++){
for(int j =0;j<M;j++){
cin>>Mt[i][j];
}
}
dp[0][0][0] = -1;
for(int i =0;i<N;i++){
for(int j =0;j<M;j++){
ll k = -1;
if(j != 0) k = max(k, Mt[i][j] + dp[0][i][j-1] - Mt[i][j-1] -1);
if(i != 0) k = max(k, Mt[i][j] + dp[0][i-1][j] - Mt[i-1][j] -1);
dp[0][i][j] = k;
}
}
dp[1][N-1][0] = -1;
for(int i =N-1;i>=0;i--){
for(int j =0;j<M;j++){
ll k = -1;
if(j != 0) k = max(k, Mt[i][j] + dp[1][i][j-1] - Mt[i][j-1] -1);
if(i != N-1) k = max(k, Mt[i][j] + dp[1][i+1][j] - Mt[i+1][j] -1);
dp[1][i][j] = k;
}
}
dp[2][0][M-1] = -1;
for(int i =0;i<N;i++){
for(int j =M-1; j>= 0;j--){
ll k = -1;
if(j != M-1) k = max(k, Mt[i][j] + dp[2][i][j+1] - Mt[i][j+1] -1);
if(i != 0) k = max(k, Mt[i][j] + dp[2][i-1][j] - Mt[i-1][j] -1);
dp[2][i][j] = k;
}
}
dp[3][N-1][M-1] = -1;
for(int i =N-1;i>=0;i--){
for(int j =M-1;j>=0;j--){
ll k = -1;
if(j != M-1) k = max(k, Mt[i][j] + dp[3][i][j+1] - Mt[i][j+1] -1);
if(i != N-1) k = max(k, Mt[i][j] + dp[3][i+1][j] - Mt[i+1][j] -1);
dp[3][i][j] = k;
}
}
ll Ans = -1;
for(int i =0;i<N;i++){
for(int j =0;j<M;j++){
for(int k =0;k<4;k++){
Ans = max(Ans, dp[k][i][j]);
}
}
}
cout<<Ans;
return 0;
}
