#include<bits/stdc++.h>
#pragma GCC optimize("Ofast,O3,unroll-loops")
using namespace std;
#define pb emplace_back
#define ALL(x) (x).begin(),(x).end()
#define rALL(x) (x).rbegin(),(x).rend()
#define srt(x) sort(ALL(x))
#define rev(x) reverse(ALL(x))
#define rsrt(x) sort(rALL(x))
#define sz(x) (int)(x.size())
#define aura 1e9
#define pii pair<int,int>
void die(string s){ puts(s.c_str()); exit(0);}
// #define int long long
const int mod=1e9+7;
int binpow(int a,int b)
{
int res=1;
while(b)
{
if(b&1)
res=res*a%mod;
b>>=1;
a=a*a%mod;
}
return res%mod;
}
int inv(int x)
{
return binpow(x,mod-2)%mod;
}
int memo[51][51][51][51];
void solve()
{
memset(memo,-1,sizeof(memo));
int n,m;
cin>>n>>m;
vector<vector<int>>a(n,vector<int>(m));
for(auto &x:a)
for(int &y:x)
cin>>y;
int ans=0;
vector<vector<int>>pref(n,vector<int>(m));
for(int i=0;i<n;++i)
for(int j=0;j<m;++j)
{
pref[i][j]=a[i][j];
if(i)
pref[i][j]+=pref[i-1][j];
if(j)
pref[i][j]+=pref[i][j-1];
if(i && j)
pref[i][j]-=pref[i-1][j-1];
}
auto get=[&](int i1,int j1,int i2,int j2)->int
{
int cur=pref[i2][j2];
if(i1)
cur-=pref[i1-1][j2];
if(j1)
cur-=pref[i2][j1-1];
if(i1 && j1)
cur+=pref[i1-1][j1-1];
return cur;
};
auto rec=[&](auto rec,int x1, int y1,int x2,int y2)->int
{
if(x1==x2 && y1==y2)
return 0;
if(~memo[x1][y1][x2][y2])
return memo[x1][y1][x2][y2];
int sum=get(x1,y1,x2,y2);
int mn=aura;
for(int i=x1;i<x2;++i)
mn=min(mn,rec(rec,x1,y1,i,y2)+rec(rec,i+1,y1,x2,y2));
for(int i=y1;i<y2;++i)
mn=min(mn,rec(rec,x1,y1,x2,i)+rec(rec,x1,i+1,x2,y2));
memo[x1][y1][x2][y2]=mn+sum;
return memo[x1][y1][x2][y2];
};
cout<<rec(rec,0,0,n-1,m-1)<<'\n';
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int t=1;
#ifdef IOI
freopen("test.in","r",stdin);
freopen("test.out","w",stdout);
#endif
// cin>>t;
while(t--)
solve();
return 0;
}
