#include <bits/stdc++.h>
using namespace std;
#define fileio() freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
#define fastio() ios_base::sync_with_stdio(0), cin.tie(0);
#define pb push_back
#define ll long long
#define sp " "
#define endl "\n"
#define modulo 100000007
#define N 18000005
#define st first
#define nd second
#define int long long
#define pii pair<int, int>
vector<int> adj[N];
int id[4005][4005], arr[4015][4005], dist[4005][4005], vis[4005][4005];
unordered_map<char, int> value;
int32_t main()
{
fastio();
//cout<<(((4005 * 4005 * 2) + 6 * N) * 4)/ (1<<20)<<endl;
int h, w;
cin>>h>>w;
value['F'] = 1, value['R'] = 2, value['.'] = 3;
int ctr = 1;
for (int i = 1; i <= h; i++)
{
for (int j = 1; j <= w; j++)
{
char tmp;
cin>>tmp;
switch(tmp)
{
case 'B':
arr[i][j] = 1;
break;
case 'T':
arr[i][j] = 2;
break;
case '*':
arr[i][j] = 3;
break;
}
//arr[i][j] = value[tmp];
}
}
int color = arr[1][1], ans = 0;
deque<pii> q;
//memset(dist, modulo, sizeof(dist));
q.push_front({1, 1});
dist[1][1] = 1;
int steps = 0;
while(!q.empty())
{
steps++;
pii top = q.front();
vis[top.st][top.nd] = 1;
int i = top.st, j = top.nd;
int d = dist[i][j];
q.pop_front();
ans = max(ans, d);
int color = arr[i][j];
if (i < h && arr[i + 1][j] == color && vis[i + 1][j] == 0)
q.push_front({i + 1, j}), dist[i + 1][j] = d;
else if (i < h && arr[i + 1][j] == 3 - color && vis[i + 1][j] == 0)
q.push_back({i + 1, j}), dist[i + 1][j] = d + 1;
if (i > 1 && arr[i - 1][j] == color && vis[i - 1][j] == 0)
q.push_front({i - 1, j}), dist[i - 1][j] = d;
else if (i > 1 && arr[i - 1][j] == 3 - color && vis[i - 1][j] == 0)
q.push_back({i - 1, j}), dist[i - 1][j] = d + 1;
if (j < w && arr[i][j + 1] == color && vis[i][j + 1] == 0)
q.push_front({i, j + 1}), dist[i][j + 1] = d;
else if (j < w && arr[i][j + 1] == 3 - color && vis[i][j + 1] == 0)
q.push_back({i, j + 1}), dist[i][j + 1] = d + 1;
if (j > 1 && arr[i][j - 1] == color && vis[i][j - 1] == 0)
q.push_front({i, j - 1}), dist[i][j - 1] = d;
else if (j > 1 && arr[i][j - 1] == 3 - color && vis[i][j - 1] == 0)
q.push_back({i, j - 1}), dist[i][j - 1] = d + 1;
}
//cout<<steps<<endl;
cout<<ans<<endl;
cerr<<"time taken : "<<(float) clock() / CLOCKS_PER_SEC<<" seconds\n";
return 0;
}
