#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main() {
int n,m; cin >> n >> m;
int arr[n][m] = {};
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
cin >> arr[i][j];
}
}
int pref[n][m] = {};
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
pref[i][j] = arr[i][j];
if (j > 0) {
pref[i][j] += pref[i][j-1];
}
if (i > 0) {
pref[i][j] += pref[i-1][j];
}
if (i > 0 and j > 0) {
pref[i][j] -= pref[i-1][j-1];
}
}
}
int dp[n][m][n][m] = {};
//dimensions
for (int k = 0; k < n; k++) {
for (int l = 0; l < m; l++) {
// top left corner
for (int i = 0; i+k < n; i++) {
for (int j = 0; j+l < m; j++) {
if (k == 0 and l == 0) {
dp[i][j][i+k][j+l] = 0;
} else {
dp[i][j][i+k][j+l] = 2e9;
//main dp process
for (int x = 0; x < k; x++) {
//consider cutting a strip of x*l
//so e.g. a 3x4 would consider 1x4,2x4 and 2x4,1x4 cuts
dp[i][j][i+k][j+l] = min(dp[i][j][i+k][j+l], dp[i][j][i+x][j+l]+dp[i+x+1][j][i+k][j+l]);
}
for (int x = 0; x < l; x++) {
//consider cutting a strip of k*x
dp[i][j][i+k][j+l] = min(dp[i][j][i+k][j+l], dp[i][j][i+k][j+x]+dp[i][j+x+1][i+k][j+l]);
}
//no matter what, this costs a specified amount to do any cut on
dp[i][j][i+k][j+l] += pref[i+k][j+l];
if (i > 0) {
dp[i][j][i+k][j+l] -= pref[i-1][j+l];
}
if (j > 0) {
dp[i][j][i+k][j+l] -= pref[i+k][j-1];
}
if (i > 0 and j > 0) {
dp[i][j][i+k][j+l] += pref[i-1][j-1];
}
}
}
}
}
}
cout << dp[0][0][n-1][m-1];
return 0;
}
