#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int nx=55;
ll n, m, qs[nx][nx], dp[nx][nx][nx][nx];
ll area(int a, int b, int c, int d)
{
return qs[c][d]-qs[c][b-1]-qs[a-1][d]+qs[a-1][b-1];
}
int main()
{
cin.tie(NULL)->sync_with_stdio(false);
cin>>n>>m;
for (int i=1; i<=n; i++) for (int j=1; j<=m; j++) cin>>qs[i][j], qs[i][j]+=qs[i-1][j]+qs[i][j-1]-qs[i-1][j-1];
for (int x=0; x<=n; x++)
{
for (int y=0; y<=m; y++)
{
for (int i=1; i+x<=n; i++)
{
for (int j=1; j+y<=m; j++)
{
if (x==0&&y==0) dp[i][j][i][j]=0;
else
{
dp[i][j][i+x][j+y]=LLONG_MAX;
for (int md=i; md<i+x; md++) dp[i][j][i+x][j+y]=min(dp[i][j][i+x][j+y], dp[i][j][md][j+y]+dp[md+1][j][i+x][j+y]+area(i, j, i+x, j+y));
for (int md=j; md<j+y; md++) dp[i][j][i+x][j+y]=min(dp[i][j][i+x][j+y], dp[i][j][i+x][md]+dp[i][md+1][i+x][j+y]+area(i, j, i+x, j+y));
}
//cout<<"debug "<<i<<' '<<j<<' '<<i+x<<' '<<j+y<<' '<<dp[i][j][i+x][j+y]<<'\n';
//cout<<"area "<<area(i, j, i+x, j+y)<<'\n';
}
}
}
}
cout<<dp[1][1][n][m];
}
