#include<bits/stdc++.h>
using namespace std;
const int N=15,M=N*N;
char g[N][N];
bool st[N][N][N][N];
int sum;
typedef pair<int, int> PII;
int a,b;
queue<PII>q;
int ans;
int bu[N][N];
int dfs(int x,int y,int x1,int y1)
{
    int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};
    memset(bu,0x3f,sizeof bu);
    q.push({x,y});
    q.push({x1,y1});
    int shu=2;
    int k=0;
    bu[x1][y1]=0;
    bu[x][y]=0;
    while(!q.empty()){
        PII p=q.front();
        q.pop();
        for(int i=0;i<4;i++){
            int hh=p.first+dx[i],tt=p.second+dy[i];
            if(hh<0||hh>=a||tt<0||tt>=b) continue;
            if(bu[hh][tt]!=0x3f3f3f3f||g[hh][tt]=='.') continue;
            q.push({hh,tt});
            shu++;
            bu[hh][tt]=bu[p.first][p.second]+1;
            k=max(k,bu[hh][tt]);
        }
    }
    if(shu==sum) return k;
    return -1;
}
int main()
{
    int t;
    cin>>t;
    int v=1;
    while(t--){
        memset(st, 0, sizeof st);
        sum=0;
        ans=1e5;
        cin>>a>>b;
        for(int i=0;i<a;i++){
            for(int j=0;j<b;j++){
                cin>>g[i][j];
                if(g[i][j]=='#') sum++;
                //cout<<g[i][j]<<' ';
            }
            //cout<<endl;
        }
        if(sum==1||sum==2){
            cout<<"Case "<<v++<<": "<<0<<endl;
            continue;
        }
        if(sum==0){
            cout<<"Case "<<v++<<": "<<-1<<endl;
            continue;
        }
        for(int i=0;i<a;i++){
            for(int j=0;j<b;j++){
                for(int k=0;k<a;k++){
                    for(int p=0;p<b;p++){
                        if(g[i][j]=='.'||g[k][p]=='.') continue;
                        if(st[i][j][k][p]) continue;
                        st[i][j][k][p]=st[k][p][i][j]=true;
                        int hh=dfs(i,j,k,p);
                        if(hh!=-1) ans=min(ans,hh);
                        //cout<<ans<<' ';
                        //cout<<i<<' '<<j<<' '<<k<<' '<<p<<endl;
                    }
                }
            }
        }
        if(ans==1e5) ans=-1;
        cout<<"Case "<<v++<<": "<<ans<<endl;
    }
    return 0;
}