#include <bits/stdc++.h>
#define _ ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define fore(i,a,b) for(lli i = (a), abcdxd = (b); i < abcdxd; i++)
#define f first
#define s second
#define ENDL '\n'
#define pb push_back
#define sz(s) lli((s).size())
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
using namespace std;
typedef long long lli;
// typedef long long LLI;
typedef pair<lli,lli> ii;
typedef vector<lli> vi;
typedef vector<ii> vii;
typedef long double ld;
#define deb(x) cout << #x << ": " << x << endl;
#define BIGLLI __int128
typedef vector<vi> mtrx;
const lli N = 55;
const lli INF = 1e18 + 12;
lli n, m;
lli v[N][N];
lli dp[N][N][N][N];
bool vis[N][N][N][N];
lli calc(lli lx, lli rx, lli ly, lli ry){
if (lx > rx or ly > ry) return 0;
if (lx == rx and ly == ry) return 0;
auto &ans = dp[lx][rx][ly][ry];
auto &mem = vis[lx][rx][ly][ry];
if (!mem){
mem = true;
ans = INF;
lli sum = 0; fore(i,lx,rx+1) fore(j,ly,ry+1) sum += v[i][j];
fore(i,lx,rx) ans = min(ans, sum + calc(lx, i, ly, ry) + calc(i+1, rx, ly, ry));
fore(j,ly,ry) ans = min(ans, sum + calc(lx, rx, ly, j) + calc(lx, rx, j+1, ry));
}
return ans;
}
void solve(){
cin >> n >> m;
fore(i,0,n) fore(j,0,m) cin >> v[i][j];
cout << calc(0, n-1, 0, m-1) << endl;
}
int main(){
// lli t; cin >> t;
// while (t--)
solve();
return 0;
}
