#include "bits/stdc++.h"
using namespace std;
// #define endl '\n'
// #define int long long
const int MXN = 55, MXM = 55;
int n, m;
int arr[MXN][MXM];
int dp[MXN][MXN][MXM][MXM];
int solve(int t, int d, int l, int r) {
if (t == d && l == r) return 0;
if (dp[t][d][l][r] != -1) return dp[t][d][l][r];
int sm = 0;
for (int i=t; i<=d; i++) {
for (int j=l; j<=r; j++) {
sm += arr[i][j];
}
}
int mx = INT_MAX;
for (int i=t; i<d; i++) {
mx = min(mx, solve(t, i, l, r) + solve(i+1, d, l, r));
}
for (int i=l; i<r; i++) {
mx = min(mx, solve(t, d, l, i) + solve(t, d, i+1, r));
}
return dp[t][d][l][r] = sm + mx;
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
memset(dp, -1, sizeof dp);
cin >> n >> m;
for (int i=0; i<n; i++) {
for (int j=0; j<m; j++) {
cin >> arr[i][j];
}
}
cout << solve(0, n-1, 0, m-1) << endl;
}
