1 #include<cstdio>
 2 #include<iostream>
 3 #include<cmath>
 4 #include<algorithm>
 5 #include<cstring>
 6 #include<cstdlib>
 7 #include<cctype>
 8 #include<vector>
 9 #include<stack>
10 #include<queue>
11 using namespace std;
12 #define enter puts("")
13 #define space putchar(' ')
14 #define Mem(a, x) memset(a, x, sizeof(a))
15 #define rg register
16 typedef long long ll;
17 typedef double db;
18 const int INF = 0x3f3f3f3f;
19 const db eps = 1e-8;
20 const int maxn = 55;
21 inline ll read()
22 {
23   ll ans = 0;
24   char ch = getchar(), last = ' ';
25   while(!isdigit(ch)) {last = ch; ch = getchar();}
26   while(isdigit(ch)) {ans = ans * 10 + ch - '0'; ch = getchar();}
27   if(last == '-') ans = -ans;
28   return ans;
29 }
30 inline void write(ll x)
31 {
32   if(x < 0) x = -x, putchar('-');
33   if(x >= 10) write(x / 10);
34   putchar(x % 10 + '0');
35 }
36
37 int n, m;
38 char a[maxn][maxn];
39 int vis[maxn][maxn], cnt = 0;
40
41 const int dx[] = {-1, 0, 1, 0}, dy[] = {0, 1, 0, -1};
42 void dfs(int x, int y, int flg)
43 {
44   vis[x][y] = flg;
45   for(int i = 0; i < 4; ++i)
46     {
47       int newx = x + dx[i], newy = y + dy[i];
48       if(newx > 0 && newx <= n && newy > 0 && newy <= m &&
49      a[newx][newy] == 'X' && !vis[newx][newy])
50     dfs(newx, newy, flg);
51     }
52 }
53
54 int dis[4][maxn][maxn], f[maxn][maxn];
55 void solve(int flg, int x, int y)
56 {
57   for(int i = 1; i <= n; ++i)
58     for(int j = 1; j <= m; ++j)
59       dis[flg][i][j] = min(dis[flg][i][j], abs(i - x) + abs(j - y));
60 }
61
62 int main()
63 {
64   n = read(); m = read();
65   for(int i = 1; i <= n; ++i) scanf("%s", a[i] + 1);
66   for(int i = 1; i <= n; ++i)
67     for(int j = 1; j <= m; ++j)
68       if(a[i][j] == 'X' && !vis[i][j])
69     dfs(i, j, ++cnt);
70   Mem(dis, 0x3f);
71   for(int i = 1; i <= n; ++i)
72     for(int j = 1; j <= m; ++j)
73       if(a[i][j] == 'X') solve(vis[i][j], i, j);
74   Mem(f, 0x3f);
75   for(int i = 1; i <= n; ++i)
76     for(int j = 1; j <= m; ++j) if(a[i][j] == 'X')
77       {
78     f[vis[i][j]][1] = min(f[vis[i][j]][1], dis[1][i][j]);
79     f[vis[i][j]][2] = min(f[vis[i][j]][2], dis[2][i][j]);
80     f[vis[i][j]][3] = min(f[vis[i][j]][3], dis[3][i][j]);
81     f[1][vis[i][j]] = f[vis[i][j]][1];
82     f[2][vis[i][j]] = f[vis[i][j]][2];
83     f[3][vis[i][j]] = f[vis[i][j]][3];
84       }
85   int ans = min(f[1][2] + f[2][3], min(f[1][3] + f[1][2], f[1][3] + f[2][3]));
86   for(int i = 1; i <= n; ++i)
87     for(int j = 1; j <= m; ++j)
88       ans = min(ans, dis[1][i][j] + dis[2][i][j] + dis[3][i][j]);
89   write(ans - 2); enter;
90   return 0;
91 }