#include <bits/stdc++.h>
using namespace std;
#define all(x) begin(x),end(x)
using pii = pair<int,int>;
using i64 = int64_t;
using i8 = int;
vector<vector<int>> raisins;
map<tuple<i8,i8,i8,i8>,i64> memo;
i64 min_cost(i8 sx,i8 sy,i8 ex,i8 ey)
{
// memoize
if(ey-sy <= 1 && ex - sx <= 1)
{
return 0;
}
if (memo.count({sx,sy,ex,ey})) return memo[{sx,sy,ex,ey}];
// rows
int cost = /* count of raisins present */ 0;
for(int i = sy; i < ey; i++) for(int j = sx; j < ex; j++) cost += raisins[i][j];
i64 mincost = INT64_MAX;
for(int i = sx+1; i < ex;i++)
{
mincost = min(mincost,min_cost(sx,sy,i,ey)+min_cost(i,sy,ex,ey));
}
for(int i = sy+1; i < ey;i++)
{
mincost = min(mincost,min_cost(sx,sy,ex,i)+min_cost(sx,i,ex,ey));
}
memo[{sx,sy,ex,ey}] = cost + mincost;
return cost + mincost;
}
int main()
{
int N,M;
cin >> N >> M;
raisins.assign(N,vector<int>(M));
for(int i = 0; i < N; i++) for(int j = 0; j < M; j++) cin >> raisins[i][j];
cout << min_cost(0,0,M,N) << "\n";
}
