#include <bits/stdc++.h> //Andrei Alexandru a.k.a Sho
using ll=long long;
using ld=long double;
int const INF=1000000005;
ll const LINF=1000000000000000005;
ll const mod=1000000007;
ld const PI=3.14159265359;
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define endl '\n'
#define CODE_START ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
ll n,m,dp[55][55][55][55],a[55][55];
void solve(ll xl,ll xr,ll yl,ll yr){
if(xl==xr&&yl==yr){
dp[xl][xr][yl][yr]=0;
return;
}
if(dp[xl][xr][yl][yr]!=LINF){
return;
}
ll sum=0;
for(ll i=xl;i<=xr;i++)
{
for(ll j=yl;j<=yr;j++)
{
sum+=a[i][j];
}
}
for(ll i=xl+1;i<=xr;i++)
{
solve(xl,i-1,yl,yr);
solve(i,xr,yl,yr);
dp[xl][xr][yl][yr]=min(dp[xl][xr][yl][yr],dp[xl][i-1][yl][yr]+dp[i][xr][yl][yr]+sum);
}
for(ll i=yl+1;i<=yr;i++)
{
solve(xl,xr,yl,i-1);
solve(xr,xr,i,yr);
dp[xl][xr][yl][yr]=min(dp[xl][xr][yl][yr],dp[xl][xr][yl][i-1]+dp[xl][xr][i][yr]+sum);
}
}
int32_t main(){
CODE_START;
cin>>n>>m;
for(ll i=1;i<=n;i++)
{
for(ll j=1;j<=m;j++)
{
cin>>a[i][j];
}
}
for(ll i=1;i<=n;i++)
{
for(ll j=1;j<=m;j++)
{
for(ll i1=i;i1<=n;i1++)
for(ll j1=j;j1<=m;j1++)
{
dp[i][i1][j][j1]=LINF;
}
}
}
solve(1,n,1,m);
cout<<dp[1][n][1][m]<<endl;
}
