#include<bits/stdc++.h>
using namespace std;
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, m;
cin >> n >> m;
string s[n+1];
for (int i = 1; i <= n; i++) cin >> s[i], s[i] = ' '+s[i];
queue<pair<int, int>> q1, q2;
if (s[1][1] == 'B') q1.push({1, 1}); else q2.push({1, 1});
int ans = 0;
vector<vector<bool>> vs(n+1, vector<bool> (m+1));
while (!q1.empty() || !q2.empty())
{
ans += !q1.empty();
while (!q1.empty())
{
int x = q1.front().first, y = q1.front().second;
q1.pop();
for (int i = 0; i < 4; i++)
{
int newX = x+dx[i];
int newY = y+dy[i];
if (min(newX, newY) < 1 || newX > n || newY > m || s[newX][newY] == '*' || vs[newX][newY]) continue;
vs[newX][newY] = 1;
if (s[newX][newY] == 'B') q1.push({newX, newY}); else q2.push({newX, newY});
}
}
ans += !q2.empty();
while (!q2.empty())
{
int x = q2.front().first, y = q2.front().second;
q2.pop();
for (int i = 0; i < 4; i++)
{
int newX = x+dx[i];
int newY = y+dy[i];
if (min(newX, newY) < 1 || newX > n || newY > m || s[newX][newY] == '*' || vs[newX][newY]) continue;
vs[newX][newY] = 1;
if (s[newX][newY] == 'T') q2.push({newX, newY}); else q1.push({newX, newY});
}
}
}
cout << ans;
return 0;
}
