#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
// author : AtabeyR
#define pb push_back
#define pii pair<int, int>
#define pll pair<ll, ll>
#define all(v) v.begin(), v.end()
#define OPT ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define sec second
#define fi first
#define int ll
#define print(k) cerr << "Ans : "; cout << k << endl;
#define ins insert
#define bpc __builtin_popcountll
#define skip continue
#define endll '\n'
#define gcd(a, b) __gcd(a, b)
#define lcm(a, b) a*b / (__gcd(a, b))
typedef long long ll;
typedef unsigned long long ull;
const int oo = 0x3F3F3F3F;
const int ooo = 0x3F3F3F3F3F3F3F3FLL;
const int mod = 998244353;
const int sz = 55;
using namespace std;
using namespace __gnu_pbds;
template<class T> using ordered_set = tree<T, null_type,less<T>, rb_tree_tag,tree_order_statistics_node_update>;
void open(string s)
{
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
int n, m, k, a[sz][sz], pref[sz][sz], dp[sz][sz][sz][sz];
int cost(int x1, int y1, int x2, int y2)
{
return pref[x2][y2] - pref[x1-1][y2] - pref[x2][y1-1] + pref[x1-1][y1-1];
}
int f(int x1, int y1, int x2, int y2)
{
if(x1 == x2 && y1 == y2)
return 0;
if(dp[x1][y1][x2][y2] != -1)
return dp[x1][y1][x2][y2];
int mn = ooo;
for(int i = y1; i<y2; i++)
mn = min(mn, f(x1, y1, x2, i) + f(x1, i+1, x2, y2) + cost(x1, y1, x2, y2));
for(int j = x1; j<x2; j++)
mn = min(mn, f(x1, y1, j, y2) + f(j+1, y1, x2, y2) + cost(x1, y1, x2, y2));
return dp[x1][y1][x2][y2] = mn;
}
void solve()
{
cin >> n >> m;
for(int i = 1; i<=n; i++)
for(int j = 1; j<=m; j++
)cin >> a[i][j];
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] + a[i][j];
memset(dp, -1, sizeof(dp));
cout << f(1, 1, n, m) << endl;
}
int32_t main()
{
// open("i");
OPT
int t = 1;
//cin >> t;
for(int i = 1; i<=t; i++)
solve();
}
