#include <bits/stdc++.h> int n, m; std::vector <std::vector <int>> g; std::vector <std::vector <std::vector <std::vector <int>>>> dp(55, std::vector <std::vector <std::vector <int>>> (55, std::vector <std::vector <int>> (55, std::vector <int> (55, 0)))); int f(int x, int xx, int y, int yy) { if (x == xx - 1 && y == yy - 1) return 0; if (dp[x][xx][y][yy]) return dp[x][xx][y][yy]; int r = 1 << 30; for (int i = x + 1; i < xx; i++) r = std::min(r, f(x, i, y, yy) + f(i, xx, y, yy)); for (int i = y + 1; i < yy; i++) r = std::min(r, f(x, xx, i, yy) + f(x, xx, y, i)); dp[x][xx][y][yy] = r + g[xx][yy] + g[x][y] - g[x][yy] - g[xx][y]; return dp[x][xx][y][yy]; } int main() { std::ios::sync_with_stdio(0); std::cin.tie(0); std::cin >> n >> m; g.resize(n + 1, std::vector <int> (m + 1)); for (int i = 1; i <= n; i++) for (int j = 1; j <= m; j++) std::cin >> g[i][j]; for (int i = 1; i <= n; i++) for (int j = 1; j <= m; j++) g[i][j] += g[i - 1][j] + g[i][j - 1] - g[i - 1][j - 1]; int ans = f(0, n, 0, m); std::cout << ans << "\n"; }