#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define sz(a) (long long) a.size()
#define endl '\n'
const long long INF = 1e18, MOD = 1e9+7;
void test_case() {
int n, m;
cin >> n >> m;
vector pref(n + 1, vector<int>(m + 1));
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
int x;
cin >> x;
pref[i][j] = pref[i - 1][j] + pref[i][j - 1] - pref[i - 1][j - 1] + x;
}
}
vector dp(n + 1, vector(m + 1, vector(n + 1, vector<ll>(m + 1, INF)))); // dp[py][px][qy][qx] P = (px, py), Q = (qx, qy)
for (int py = 1; py <= n; py++) {
for (int px = 1; px <= m; px++) {
dp[py][px][py - 1][px - 1] = 0;
}
}
auto range = [&](int py, int px, int qy, int qx) {
return pref[py][px] - pref[py][qx] - pref[qy][px] + pref[qy][qx];
};
for (int py = 1; py <= n; py++) {
for (int px = 1; px <= m; px++) {
for (int qy = py - 1; qy >= 0; qy--) {
for (int qx = px - 1; qx >= 0; qx--) {
if (qy == py - 1 and qx == px - 1) continue;
// now i try to make some horizontal cut
for (int cuty = py - 1; cuty > qy; cuty--) {
dp[py][px][qy][qx] = min(dp[py][px][qy][qx], dp[py][px][cuty][qx] + dp[cuty][px][qy][qx]);
}
// now i try to make some vertical cut
for (int cutx = px - 1; cutx > qx; cutx--) {
dp[py][px][qy][qx] = min(dp[py][px][qy][qx], dp[py][px][qy][cutx] + dp[py][cutx][qy][qx]);
}
dp[py][px][qy][qx] += range(py, px, qy, qx);
}
}
}
}
cout << dp[n][m][0][0] << endl;
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int tt = 1;
//cin >> tt;
while (tt--) {
test_case();
}
return 0;
}
