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

#define x first
#define y second

using namespace std;

typedef pair<int, int> PII;

const int N = 55;

int n, m;
char g[N][N];
vector<PII> points[2];
int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};

void dfs(int a, int b, vector<PII>& q)
{
    q.push_back({a, b});
    g[a][b] = '.';

    for (int i = 0; i < 4; i ++ )
    {
        int x = a + dx[i], y = b + dy[i];
        if (x >= 0 && x < n && y >= 0 && y < m && g[x][y] == 'X')
            dfs(x, y, q);
    }
}

int main()
{
    scanf("%d%d", &n, &m);
    for (int i = 0; i < n; i ++ ) scanf("%s", g[i]);

    int k = 0;
    for (int i = 0; i < n; i ++ )
        for (int j = 0; j < m; j ++ )
            if (g[i][j] == 'X')
                dfs(i, j, points[k ++ ]);

    int res = 110;
    for (auto& a: points[0])
        for (auto& b: points[1])
            res = min(res, abs(a.x - b.x) + abs(a.y - b.y));

    printf("%d\n", res - 1);
    return 0;
}