#include <bits/stdc++.h>
using namespace std;
int n,m,sum=0,maxx=0,num=1e9+5;
int a[10][10],flag[10][10];
int ansx[4]={0,0,-1,1},ansy[4]={1,-1,0,0};

void dfs(int x,int y,int currentsum,int currentnum){
    flag[x][y]=1;currentsum+=a[x][y];currentnum++;
    if(currentsum>=sum/2){
        if(currentsum==sum/2)num=min(currentnum,num);
        flag[x][y]=0;
        return;}
    for(int i=0;i<4;i++){
        int tx=x+ansx[i],ty=y+ansy[i];
        if(!flag[tx][ty] && tx<n&&tx>=0 && ty<m&&ty>=0){
            dfs(tx,ty,currentsum,currentnum);
            flag[tx][ty]=0;}
    }
}
int main()
{
    scanf("%d%d",&m,&n);
    for(int i=0;i<n;i++)
        for(int j=0;j<m;j++){
            scanf("%d",&a[i][j]);
            sum+=a[i][j];
            maxx=max(maxx,a[i][j]);}
    if(maxx>sum/2 || sum%2){printf("0\n");return 0;}
    dfs(0,0,0,0);
    printf("%d\n",num);
}