#include <iostream>
#include <vector>
#include <algorithm>
#define int int64_t
using namespace std;
struct orchard
{
vector<vector<int>> orchard;
vector<vector<int>> table;
int n, m;
void createtable()
{
table.resize(n + 1, vector<int>(m + 1));
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m; j++)
{
table[i + 1][j + 1] = table[i + 1][j] + table[i][j + 1] - table[i][j] + orchard[i][j];
}
}
//printtable();
int mmin = 10000000000;
for (int x1 = 1; x1 <= n; x1++)
{
for (int y1 = 0; y1 <= m; y1++)
{
for (int x2 = 0; x2 < x1; x2++)
{
for (int y2 = 0; y2 < y1; y2++)
{
int in = prefsum(x1, y1, x2, y2);
int wrongin = (x1 - x2) * (y1 - y2) - in;
int wrongout = prefsum(n, m, 0, 0) - in;
mmin = min(mmin, wrongin + wrongout);
}
}
}
}
cout << mmin << "\n";
}
void printtable()
{
for (auto t : table)
{
for (auto i : t)
{
cout << i << " ";
}
cout << "\n";
}
cout << "\n";
}
int prefsum(int x1, int y1, int x2, int y2)
{
return table[x1][y1] + table[x2][y2] - table[x1][y2] - table[x2][y1];
}
};
signed main()
{
int n, m;
cin >> n >> m;
orchard orch;
orch.n = n;
orch.m = m;
orch.orchard.resize(n, vector<int>(m));
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m; j++)
{
cin >> orch.orchard[i][j];
}
}
orch.createtable();
}
