#include<bits/stdc++.h>
using namespace std;
using ll=long long;
int t[51][51];
ll p[51][51];
ll dp[52][52][52][52];
int n,m;
ll get(int y1, int x1, int y2, int x2){
return p[y2][x2]-p[y1-1][x2]-p[y2][x1-1]+p[y1-1][x1-1];
}
ll solve(int y1, int x1, int y2, int x2){
if(dp[y1][x1][y2][x2]==-1){
if(y1==y2 and x1==x2)
dp[y1][x1][y2][x2]=0;
else{
ll res=1e18;
for(int i=y1+1;i<=y2;++i){
ll pay=solve(y1,x1,i-1,x2)+solve(i,x1,y2,x2);
res=min(res,pay);
}
for(int i=x1+1;i<=x2;++i){
ll pay=solve(y1,x1,y2,i-1)+solve(y1,i,y2,x2);
res=min(res,pay);
}
dp[y1][x1][y2][x2]=res+get(y1,x1,y2,x2);
}
}
return dp[y1][x1][y2][x2];
}
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
cin>>n>>m;
for(int i=1;i<=n;++i)
for(int j=1;j<=m;++j){
cin>>t[i][j];
p[i][j]=t[i][j]+p[i-1][j]+p[i][j-1]-p[i-1][j-1];
}
memset(dp,-1,sizeof(dp));
cout<<solve(1,1,n,m);
}
