#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define endl "\n"
const int MOD = 1e9 + 7;
int dp[50][50][50][50];
int solve2(vector<vector<int>>& table){
int n = table.size();
int m = table[0].size();
vector<vector<int>> prefix(n, vector<int>(m, 0));
for(int i = 0; i < n; i++){
prefix[i][0] = table[i][0];
for(int j = 1; j < m; j++){
prefix[i][j] = prefix[i][j-1] + table[i][j];
}
}
function<int(int, int, int, int)> DFS = [&](int lx, int rx, int ly, int ry){
if(rx - lx == 0 && ry - ly == 0) return 0;
if(dp[lx][rx][ly][ry] == -1){
int ans = 2e9;
for(int i = ly; i < ry; i++){
ans = min(ans, DFS(lx, rx, ly, i) + DFS(lx, rx, i + 1, ry));
}
for(int i = lx; i < rx; i++){
ans = min(ans, DFS(lx, i, ly, ry) + DFS(i + 1, rx, ly, ry));
}
for(int i = ly; i <= ry; i++){
ans += prefix[i][rx];
if(lx > 0) ans -= prefix[i][lx - 1];
}
dp[lx][rx][ly][ry] = ans;
return (int)ans;
}else return dp[lx][rx][ly][ry];
};
return DFS(0, m - 1, 0, n - 1);
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
//freopen("inpt.txt", "r", stdin);
//freopen("out.txt", "w", stdout);
//int tt; cin >> tt;
int n, m; cin >> n >> m;
vector<vector<int>> table(n, vector<int>(m));
for(int i = 0; i < n; i++){
for(int j = 0; j < m; j++){
cin >> table[i][j];
}
}
for(int i = 0; i < n; i++){
for(int j = 0; j < m; j++){
for(int q = 0; q < m; q++){
for(int l = 0; l < n; l++){
dp[j][q][l][i] = -1;
}
}
}
}
cout << solve2(table)<< endl;
}
