#include<bits/stdc++.h>
#include<fstream>
using namespace std;
//ifstream fin("INTERNET.INP");
//ofstream fout("INTERNET.OUT");
#define ll long long
#define vt vector
#define pb push_back
#define fi first
#define se second
#define forr(i, a, b) for(int i = a; i < b; i++)
#define dorr(i, a, b) for(int i = a; i >= b; i--)
#define pii pair<int, int>
#define pll pair<ll, ll>
#define int long long
typedef unsigned long long ull;
const int mxn = 1e3;
int d[51][51][51][51];
int n, m;
int p[51][51], a[51][51];
int get(int a, int b, int c, int d){
return(p[c][d] - p[a - 1][d] - p[c][b - 1] + p[a - 1][b - 1]);
}
signed main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m;
for(int i = 1; i <= n; i++){
for(int j = i; j <= n; j++){
for(int k = 1; k <= m; k++){
for(int l = k; l <= m; l++){
d[i][j][k][l] = 1e9;
}
}
}
}
for(int i = 1; i <= n; i++){
for(int j = 1; j <= m; j++){
cin >> a[i][j];
p[i][j] = p[i - 1][j] + p[i][j - 1] - p[i - 1][j - 1] + a[i][j];
d[i][i][j][j] = 0;
}
}
for(int i = n; i >= 1; i--){
for(int j = i; j <= n; j++){
for(int k = m; k >= 1; k--){
for(int l = k; l <= m; l++){
for(int h = i; h < j; h++){
d[i][j][k][l] = min(d[i][j][k][l], d[i][h][k][l] + d[h + 1][j][k][l]);
}
for(int h = k; h < l; h++){
d[i][j][k][l] = min(d[i][j][k][l], d[i][j][k][h] + d[i][j][h + 1][l]);
}
d[i][j][k][l] += get(i, k, j, l);
}
}
}
}
cout << d[1][n][1][m] - get(1, 1, n, m);
return 0;
}
