//----------------------------------------------AC code----------------------------------------------//

#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdio>

#define f(a, b) ((a-1)*m+b)

using namespace std;

const int MAXN = 305;
int T, n, m, cnt;
char g[MAXN][MAXN];
int dx[] = {0, 1};
int dy[] = {1, 0};

struct Edge{
    int nxt, to;
}edge[MAXN*MAXN<<3];

int head[MAXN*MAXN], edge_num;
void add_edge(int from, int to){
    edge[++edge_num].nxt = head[from];
    edge[edge_num].to = to;
    head[from] = edge_num;
}

bool flag;
int dfn[MAXN*MAXN], low[MAXN*MAXN], dfsn;
void tarjan(int u, int f){
    int child = 0;
    dfn[u] = low[u] = ++dfsn;
    for(int i = head[u]; i; i = edge[i].nxt){
        if(!dfn[edge[i].to]){
            child++;
            tarjan(edge[i].to, u);
            low[u] = min(low[u], low[edge[i].to]);
            if(f == 0 && child > 1)
                flag = 1;
            if(f != 0 && low[edge[i].to] >= dfn[u])
                flag = 1;
        }
        else
            if(edge[i].to != f)
                low[u] = min(low[u], dfn[edge[i].to]);
    }
}


int main(){
    freopen("board.in", "r", stdin);
    freopen("board.out", "w", stdout);
    scanf("%d", &T);
    while(T--){
        flag = 0;
        memset(low, 0, sizeof low);
        memset(dfn, 0, sizeof dfn);
        dfsn = 0;
        edge_num = 0;
        memset(head, 0, sizeof head);
        memset(edge, 0, sizeof edge);
        memset(g, 0, sizeof g);
        cnt = 0;
        scanf("%d%d", &n, &m);
        for(int i = 1; i <= n; i++)
            scanf("%s", g[i]+1);
        for(int i = 1; i <= n; i++)
            for(int j = 1; j <= m; j++)
                if(g[i][j] == '#')
                    cnt++;
        if(cnt <= 2){
            puts("-1");
            continue;
        }
        for(int i = 1; i <= n; i++){
            for(int j = 1; j <= m; j++){
                if(g[i][j] == '#'){
                    for(int k = 0; k < 2; k++){
                        int tx = i + dx[k];
                        int ty = j + dy[k];
                        if(1 <= tx && tx <= n && 1 <= ty && ty <= m && g[tx][ty] == '#'){
                            add_edge(f(i, j), f(tx, ty));
                            add_edge(f(tx, ty), f(i, j));
                        }
                    }
                }
            }
        }
        for(int i = 1; i <= n; i++)
            for(int j = 1; j <= m; j++)
                if(g[i][j] == '#' && !dfn[f(i, j)])
                    tarjan(f(i, j), 0);
        if(flag)
            puts("1");
        else
            puts("2");
    }
    return 0;
}