#include <bits/stdc++.h>
using namespace std;
int n,m;
///Dynamic Programming
///Bottom-Up
///Determine the minimum number of raisins needed to pay (sums)
int A[55][55];
int sum[55][55];
int memo[55][55][55][55];
int getSum(int i,int j,int a,int b)
{
int total=sum[j][b]-sum[j][a-1]-sum[i-1][b]+sum[i-1][a-1];
return total;
}
int MinCost(int i,int j,int a,int b)
{
if(i==j && a==b)
return 0;
if(memo[i][j][a][b]==-1){
int minimum=INT_MAX;
for(int i_nxt=i;i_nxt<j;i_nxt++){
minimum=min(minimum,MinCost(i,i_nxt,a,b)
+MinCost(i_nxt+1,j,a,b)
+getSum(i,j,a,b));
}
for(int a_nxt=a;a_nxt<b;a_nxt++){
minimum=min(minimum,MinCost(i,j,a,a_nxt)
+MinCost(i,j,a_nxt+1,b)
+getSum(i,j,a,b));
}
memo[i][j][a][b]=minimum;
}
return memo[i][j][a][b];
}
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);
cin>>n>>m;
for(int i=1;i<=n;i++){
for(int j=1;j<=m;j++){
cin>>A[i][j];
sum[i][j]=sum[i-1][j]+sum[i][j-1]-sum[i-1][j-1]+A[i][j];
}
}
for(int szRows=1;szRows<=n;szRows++){
for(int szCols=1;szCols<=m;szCols++){
for(int i=1;i<=n-szRows+1;i++){
int j=i+szRows-1;
for(int a=1;a<=m-szCols+1;a++){
int b=a+szCols-1;
if(i==j && a==b){
memo[i][j][a][b]=0;
continue;
}
memo[i][j][a][b]=INT_MAX;
for(int nxt_i=i;nxt_i<j;nxt_i++){
memo[i][j][a][b]=min(memo[i][j][a][b],
memo[i][nxt_i][a][b]
+memo[nxt_i+1][j][a][b]
+getSum(i,j,a,b));
}
for(int nxt_a=a;nxt_a<b;nxt_a++){
memo[i][j][a][b]=min(memo[i][j][a][b],
memo[i][j][a][nxt_a]
+memo[i][j][nxt_a+1][b]
+getSum(i,j,a,b));
}
}
}
}
}
cout<<memo[1][n][1][m]<<'\n';
return 0;
}
