#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
int r, c; cin >> r >> c;
vector<vector<int>> grid(r, vector<int>(c));
vector<vector<vector<vector<int>>>> dp(r, vector<vector<vector<int>>>(c, vector<vector<int>>(r, vector<int>(c, 1e8)))); // dp[dr][dc][sr][sc]
for (int i = 0; i < r; i++) {
for (int j = 0; j < c; j++) {
cin >> grid[i][j];
dp[0][0][i][j] = 0;
}
}
for (int i = 0; i < r; i++){
for (int j = 1; j < c; j++){
grid[i][j] += grid[i][j - 1];
}
}
for (int i = 1; i < r; i++){
for (int j = 0; j < c; j++){
grid[i][j] += grid[i - 1][j];
}
}
for (int dr = 0; dr < r; dr++){
for (int dc = 0; dc < c; dc++){
if (dr == 0 && dc == 0) continue;
for (int sr = 0; sr + dr < r; sr++){
for (int sc = 0; sc + dc < c; sc++){
int base = grid[sr + dr][sc + dc];
if (sr > 0) base -= grid[sr - 1][sc + dc];
if (sc > 0) base -= grid[sr + dr][sc - 1];
if (sr > 0 && sc > 0) base += grid[sr - 1][sc - 1];
for (int ddr = 1; ddr <= dr; ddr++){
dp[dr][dc][sr][sc] = min(dp[dr][dc][sr][sc], base + dp[ddr - 1][dc][sr][sc] + dp[dr - ddr][dc][sr + ddr][sc]);
}
for (int ddc = 1; ddc <= dc; ddc++){
dp[dr][dc][sr][sc] = min(dp[dr][dc][sr][sc], base + dp[dr][ddc - 1][sr][sc] + dp[dr][dc - ddc][sr][sc + ddc]);
}
}
}
}
}
cout << dp[r - 1][c - 1][0][0] << "\n";
}
