#include <algorithm>
#include <iostream>
#include <numeric>
#include <cassert>
#include <vector>
#include <queue>
#include <set>
typedef long long llong;
const int MAXN = 50 + 10;
const int INF = 2e9;
int n, m, p;
int a[MAXN][MAXN];
int prefix[MAXN][MAXN];
llong dp[MAXN][MAXN][MAXN][MAXN];
bool bl[MAXN][MAXN][MAXN][MAXN];
llong f(int rowS, int colS, int rowE, int colE)
{
if (rowS == rowE && colS == colE)
{
return 0;
}
if (bl[rowS][colS][rowE][colE])
{
return dp[rowS][colS][rowE][colE];
}
bl[rowS][colS][rowE][colE] = true;
dp[rowS][colS][rowE][colE] = INF;
int sum = prefix[rowE][colE] - prefix[rowS - 1][colE] - prefix[rowE][colS - 1] + prefix[rowS - 1][colS - 1];
for (int at = rowS ; at < rowE ; ++at)
{
dp[rowS][colS][rowE][colE] = std::min(dp[rowS][colS][rowE][colE], f(rowS, colS, at, colE) + f(at + 1, colS, rowE, colE) + sum);
}
for (int at = colS ; at < colE ; ++at)
{
dp[rowS][colS][rowE][colE] = std::min(dp[rowS][colS][rowE][colE], f(rowS, colS, rowE, at) + f(rowS, at + 1, rowE, colE) + sum);
}
return dp[rowS][colS][rowE][colE];
}
void solve()
{
for (int i = 1 ; i <= n ; ++i)
{
for (int j = 1 ; j <= m ; ++j)
{
prefix[i][j] = a[i][j] + prefix[i - 1][j] + prefix[i][j - 1] - prefix[i - 1][j - 1];
}
}
std::cout << f(1, 1, n, m) << '\n';
}
void input()
{
std::cin >> n >> m;
for (int i = 1 ; i <= n ; ++i)
{
for (int j = 1 ; j <= m ; ++j)
{
std::cin >> a[i][j];
}
}
}
void fastIOI()
{
std::ios_base :: sync_with_stdio(0);
std::cout.tie(nullptr);
std::cin.tie(nullptr);
}
int main()
{
fastIOI();
input();
solve();
return 0;
}
