#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define sp <<" "<<
#define endl "\n"
vector<vector<ll>> grid, pref;
ll query(int lr, int rr, int lc, int rc) {
return { 0
+ pref[rr][rc]
- (lr > 0 ? pref[lr-1][rc] : 0)
- (lc > 0 ? pref[rr][lc-1] : 0)
+ (lr > 0 and lc > 0 ? pref[lr-1][lc-1] : 0)
};
}
ll decomp(int lr, int rr, int lc, int rc) {
ll res = query(lr, rr, lc, rc);
ll sz = (rr - lr + 1) * (rc - lc + 1);
if (sz < 2) return 0;
if (sz > 2) {
ll mn = LLONG_MAX;
int lr1, rr1, lc1, rc1, lr2, rr2, lc2, rc2;
for (int i = lr; i < rr; i++) {
ll q1 = query(lr, i, lc, rc), q2 = query(i+1, rr, lc, rc);
ll diff = abs(q1 - q2);
if (diff < mn) {
mn = diff;
lr1 = lr, rr1 = i, lc1 = lc, rc1 = rc;
lr2 = i+1, rr2 = rr, lc2 = lc, rc2 = rc;
}
}
for (int i = lc; i < rc; i++) {
ll q1 = query(lr, rr, lc, i), q2 = query(lr, rr, i+1, rc);
ll diff = abs(q1 - q2);
if (diff < mn) {
mn = diff;
lr1 = lr, rr1 = rr, lc1 = lc, rc1 = i;
lr2 = lr, rr2 = rr, lc2 = i+1, rc2 = rc;
}
}
res += decomp(lr1, rr1, lc1, rc1);
res += decomp(lr2, rr2, lc2, rc2);
}
return res;
}
void solve() {
int n, m; cin >> n >> m;
grid.assign(n, vector<ll>(m));
pref.assign(n, vector<ll>(m));
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
cin >> grid[i][j];
}
}
pref = grid;
for (int i = 1; i < n; i++) pref[i][0] += pref[i-1][0];
for (int i = 1; i < m; i++) pref[0][i] += pref[0][i-1];
for (int i = 1; i < n; i++) {
for (int j = 1; j < m; j++) {
pref[i][j] += pref[i-1][j] + pref[i][j-1] - pref[i-1][j-1];
}
}
cout << decomp(0, n-1, 0, m-1) << endl;
}
signed main() {
cin.tie(0);
ios_base::sync_with_stdio(false);
int t = 1;
// cin >> t;
while (t--)
solve();
}
