#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<vvi> v3i;
typedef vector<v3i> v4i;
#define INF(dt) numeric_limits<dt>::max()
#define NINF(dt) numeric_limits<dt>::min()
#define pb push_back
int main() {
int n, m;
cin >> n >> m;
vvi g(n + 1, vi(m + 1, 0));
for(int i = 1; i <= n; i++) {
for(int j = 1; j <= m; j++) {
cin >> g[i][j];
g[i][j] += g[i][j - 1];
g[i][j] += g[i - 1][j];
g[i][j] -= g[i - 1][j - 1];
}
}
v4i dp(n, v3i(m, vvi(n, vi(m, INF(int)))));
for(int i = 0; i < n; i++) {
for(int j = 0; j < m; j++) {
dp[i][j][i][j] = 0;
}
}
for(int iw = 0; iw < n; iw++) {
for(int jw = 0; jw < m; jw++) {
for(int i = 0; i < n; i++) {
for(int j = 0; j < m; j++) {
int i2 = i + iw, j2 = j + jw;
if(i2 >= n || j2 >= m) continue;
int& ans = dp[i][j][i2][j2];
int cursum = g[i2 + 1][j2 + 1] - g[i][j2 + 1] - g[i2 + 1][j] + g[i][j];
/*
row cut
*/
for(int k = i; k < i2; k++) {
ans = min(ans, dp[k + 1][j][i2][j2] + dp[i][j][k][j2] + cursum);
}
/*
col cut
*/
for(int k = j; k < j2; k++) {
ans = min(ans, dp[i][k + 1][i2][j2] + dp[i][j][i2][k] + cursum);
}
}
}
}
}
cout << dp[0][0][n - 1][m - 1] << endl;
return 0;
}
