#include <iostream>
#include <vector>
#include <algorithm>
using std::cout;
using std::endl;
using std::vector;
/**
* https://oj.uz/problem/view/IOI09_raisins
* 2 3
* 2 7 5
* 1 9 5 should output 77
*/
int main() {
int row_num;
int col_num;
std::cin >> row_num >> col_num;
vector<vector<int>> choco_prefs(row_num + 1, vector<int>(col_num + 1));
for (int r = 1; r <= row_num; r++) {
for (int c = 1; c <= col_num; c++) {
std::cin >> choco_prefs[r][c];
choco_prefs[r][c] += choco_prefs[r - 1][c]
+ choco_prefs[r][c - 1]
- choco_prefs[r - 1][c - 1];
}
}
auto sum = [&] (int rs, int cs, int re, int ce) {
return choco_prefs[re + 1][ce + 1]
- choco_prefs[rs][ce + 1]
- choco_prefs[re + 1][cs]
+ choco_prefs[rs][cs];
};
vector<vector<vector<vector<int>>>> min_pay(
row_num, vector<vector<vector<int>>>(
col_num, vector<vector<int>>(row_num, vector<int>(col_num))
)
);
for (int height = 1; height <= row_num; height++) {
for (int width = 1; width <= col_num; width++) {
if (height == 1 && width == 1) {
continue; // for a 1x1 block of chocolate the ans is always 0
}
for (int r = 0; r <= row_num - height; r++) {
for (int c = 0; c <= col_num - width; c++) {
int& curr = min_pay[r][c][r + height - 1][c + width - 1];
curr = INT32_MAX;
int cost = sum(r, c, r + height - 1, c + width - 1);
for (int hor_split = 1; hor_split < width; hor_split++) {
curr = std::min(
curr,
cost
+ min_pay[r][c][r + height - 1][c + hor_split - 1]
+ min_pay[r][c + hor_split][r + height - 1][c + width - 1]
);
}
for (int vert_split = 1; vert_split < height; vert_split++) {
curr = std::min(
curr,
cost
+ min_pay[r][c][r + vert_split - 1][c + width - 1]
+ min_pay[r + vert_split][c][r + height - 1][c + width - 1]
);
}
}
}
}
}
cout << min_pay[0][0][row_num - 1][col_num - 1] << endl;
}
