#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> PII;
const int N = 105, INF = 0x3f3f3f3f;
vector<int> G[N];
int n, m, a[105], b[15], dp[N][1 << 10];
bool vis[N];

int id(int i, int j) { return (i - 1) * m + j; }

void dijkstra(int s) {
    memset(vis, 0, sizeof(vis));
    priority_queue<PII, vector<PII>, greater<PII>> q;
    for (int i = 1; i <= n * m; i++)
        if (dp[i][s] != INF)
            q.push({dp[i][s], i});
    while (!q.empty()) {
        int x = q.top().second;
        q.pop();
        if (vis[x]) continue;
        vis[x] = 1;
        for (int y : G[x]) {
            if (dp[y][s] > dp[x][s] + a[y]) {
                dp[y][s] = dp[x][s] + a[y];
                q.push({dp[y][s], y});
            }
        }
    }
}

int main() {
    scanf("%d%d", &n, &m);
    int k = 0;
    memset(dp, 0x3f, sizeof(dp));
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++) {
            int p = id(i, j);
            scanf("%d", &a[p]);
            if (a[p] == 0) {
                b[++k] = p;
                dp[b[k]][1 << (k - 1)] = 0;
            }
            if (i > 1) {
                int x = id(i - 1, j), y = id(i, j);
                G[x].push_back(y);
                G[y].push_back(x);
            }
            if (j > 1) {
                int x = id(i, j - 1), y = id(i, j);
                G[x].push_back(y);
                G[y].push_back(x);
            }
        }

    for (int S = 1; S < (1 << k); S++) {
        for (int s = S - 1; s; s = S & (s - 1))
            for (int i = 1; i <= n * m; i++)
                dp[i][S] = min(dp[i][S], dp[i][s] + dp[i][S ^ s] - a[i]);
        dijkstra(S);
    }
    printf("%d\n", dp[b[1]][(1 << k) - 1]);
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> PII;
const int N=105, INF=0x3f3f3f3f;
vector<int>G[N];
using namespace std;  
int n,m,a[105],b[15],dp[N][1<<10];bool vis[N]; 
int id(int i,int j){ return (i-1)*m+j;} 
void dijkstra(int s)
{
	memset(vis, 0, sizeof(vis));
    priority_queue<PII,vector<PII>,greater<PII>> q;
	for(int i=1;i<=n*m;i++)if(dp[i][ s ]!=INF)q.push({dp[i][ s ],i});
	while(!q.empty())
	{
		int x=q.top().second;q.pop();
		if(vis[x])continue;
		vis[x]=1;
		for(int y:G[x])
		{
			if(dp[y][ s ]>dp[x][ s ]+a[y])
			{
				dp[y][ s ]=dp[x][ s ]+a[y];
				q.push({dp[y][ s ],y});
			}
		}
	}
}
  
int main()  
{   
    scanf("%d%d",&n,&m);
    int k=0;
    memset(dp,0x3f,sizeof(dp));
    for(int i=1;i<=n;i++)for(int j=1;j<=m;j++)
    {
        int p=id(i,j);
        scanf("%d",&a[p]);
        if(a[p]==0)
        {
            b[++k]=p;
            dp[b[k]][1<<(k-1)]=0;
        }
        if(i>1)
        {
            int x=id(i-1,j),y=id(i,j);
            G[x].push_back(y);
            G[y].push_back(x);
        }
        if(j>1)
        {
            int x=id(i,j-1),y=id(i,j);
            G[x].push_back(y);
            G[y].push_back(x);
        }
    }

	for(int S=1;S<(1<<k);S++)
	{
		for(int s=S-1;s;s=S&(s-1))
			for(int i=1;i<=n*m;i++)
                dp[i][ S ]=min(dp[i][ S ],dp[i][ s ]+dp[i][S^s]-a[i]);
		dijkstra(S);
	}
	printf("%d\n",dp[b[1]][(1<<k)-1]);
	return 0;
}