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

#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];//分别存储两个连通块的点坐标

int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};

void dfs(int x, int y, vector<PII>& ps)
{
    g[x][y] = '.';
    ps.push_back({x, y});

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

int main()
{
    cin >> n >> m;
    for (int i = 0; i < n; i ++ ) cin >> g[i];

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

    int res = 1e8;
    for (auto& a: points[0])
        for (auto& b: points[1])
            res = min(res, abs(a.x - b.x) + abs(a.y - b.y) - 1);

    cout << res << endl;
    return 0;
}