// EXPLOSION!
#define _CRT_SECURE_NO_WARNINGS
#include<bits/stdc++.h>
#include<unordered_set>
#include<unordered_map>
#include<chrono>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pair<int, int>> vpi;
typedef vector<pair<ll, ll>> vpll;
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)
#define pb push_back
#define mp make_pair
#define rsz resize
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define f first
#define s second
#define cont continue
#define endl '\n'
//#define ednl '\n'
#define test int testc;cin>>testc;while(testc--)
#define pr(a, b) trav(x,a)cerr << x << b; cerr << endl;
#define message cout << "Hello World" << endl;
const int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 }; // for every grid problem!!
const ll linf = 4000000000000000000LL;
const ll inf = 1000000007;//998244353
const ld pi = 3.1415926535;
void pv(vi a) { trav(x, a)cout << x << " "; cout << endl; }void pv(vll a) { trav(x, a)cout << x << " "; cout << endl; }void pv(vector<vi>a) {
F0R(i, sz(a)) { cout << i << endl; pv(a[i]); cout << endl; }
}void pv(vector<vll>a) { F0R(i, sz(a)) { cout << i << endl; pv(a[i]); }cout << endl; }void pv(vector<string>a) { trav(x, a)cout << x << endl; cout << endl; }
void setIO(string s) {
ios_base::sync_with_stdio(0); cin.tie(0);
if (sz(s))
{
freopen((s + ".in").c_str(), "r", stdin);
if (s != "test1")
freopen((s + ".out").c_str(), "w", stdout);
}
}
int n, m;
const int MAX = 52;
ll dp[MAX][MAX][MAX][MAX];
int a[MAX][MAX], prefix[MAX][MAX];
int get(int xl, int xr, int yl, int yr)
{
return prefix[xr + 1][yr + 1] - prefix[xr + 1][yl] - prefix[xl][yr + 1] + prefix[xl][yl];
}
int main()
{
setIO("");
cin >> n >> m;
F0R(i, n)
{
F0R(j, m)
{
cin >> a[i][j];
}
}
F0R(i, n)F0R(j, m)prefix[i + 1][j + 1] = prefix[i + 1][j] + prefix[i][j + 1] - prefix[i][j] + a[i][j];
F0R(a, n)F0R(b, n)F0R(c, m)F0R(d, m)
{
dp[a][b][c][d] = linf;
}
R0F(xl, n)
{
R0F(yl, m)
{
dp[xl][xl][yl][yl] = 0;
FOR(yr, yl + 1, m)
{
FOR(k, yl, yr)
{
dp[xl][xl][yl][yr] = min(dp[xl][xl][yl][yr], dp[xl][xl][yl][k] + dp[xl][xl][k + 1][yr] + get(xl, xl, yl, yr));
}
}
}
FOR(xr, xl + 1, n)
{
R0F(yl, m)
{
FOR(k, xl, xr)dp[xl][xr][yl][yl] = min(dp[xl][xr][yl][yl], dp[xl][k][yl][yl] + dp[k + 1][xr][yl][yl] + get(xl, xr, yl, yl));
FOR(yr, yl + 1, m)
{
FOR(k, xl, xr)
{
dp[xl][xr][yl][yr] = min(dp[xl][xr][yl][yr], dp[xl][k][yl][yr] + dp[k + 1][xr][yl][yr] + get(xl, xr, yl, yr));
}
FOR(k, yl, yr)
{
dp[xl][xr][yl][yr] = min(dp[xl][xr][yl][yr], dp[xl][xr][yl][k] + dp[xl][xr][k + 1][yr] + get(xl, xr, yl, yr));
}
}
}
}
}
cout << dp[0][n - 1][0][m - 1] << endl;
}
