#include <bits/stdc++.h>
#define x first
#define y second
#define pii pair<ll, ll>
typedef long long ll;
const ll MOD = 1000000007LL;
const ll INF = 1e15;
using namespace std;
ll n, m, a[60][60], a1, b1, a2, b2, tmp;
ll dp[60][60][60][60];
int main() {
cin.tie(0); cout.tie(0);
ios::sync_with_stdio(0);
cin >> n >> m;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
for (int p = 1; p <= n; p++) {
for (int q = 1; q <= m; q++) dp[i][j][p][q] = INF;
}
}
}
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
cin >> a[i][j];
dp[i][j][i][j] = 0;
a[i][j] += a[i-1][j]+a[i][j-1]-a[i-1][j-1];
}
}
for (int dx = 1; dx <= n; dx++) {
for (int dy = 1; dy <= m; dy++) {
for (int i = 1; i <= n-dx+1; i++) {
for (int j = 1; j <= m-dy+1; j++) {
a1 = i, b1 = j;
a2 = i+dx-1, b2 = j+dy-1;
tmp = a[a2][b2]-a[a1-1][b2]-a[a2][b1-1]+a[a1-1][b1-1];
for (int k = a1; k < a2; k++) {
dp[a1][b1][a2][b2] = min(dp[a1][b1][a2][b2], dp[a1][b1][k][b2]+dp[k+1][b1][a2][b2]+tmp);
}
for (int k = b1; k < b2; k++) {
dp[a1][b1][a2][b2] = min(dp[a1][b1][a2][b2], dp[a1][b1][a2][k]+dp[a1][k+1][a2][b2]+tmp);
}
// cout << a1 << ' ' << b1 << ' ' << a2 << ' ' << b2 << ' ' << tmp << ' ' << dp[a1][b1][a2][b2] << "\n";
}
}
// cout << "\n";
}
// cout << "\n";
}
cout << dp[1][1][n][m] << "\n";
return 0;
}
