#include <bits/stdc++.h>
using namespace std;
template<typename T>
void out(T x) { cout << x << endl; exit(0); }
#define watch(x) cout << (#x) << " is " << (x) << endl
const int maxn = 1010;
int n, m;
string g[maxn];
bool viz[maxn][maxn];
int cc = 0;
vector<pair<int,int>> moves = { {-1,0}, {1,0}, {0,-1}, {0,1} };
vector<pair<int,int>> qq;
void dfs(int x, int y, char c) {
if (x<0||y<0||x>=n||y>=m) return;
if (viz[x][y]) return;
if (g[x][y]==c) {
viz[x][y]=true;
qq.push_back({x,y});
dfs(x-1,y,c);
dfs(x+1,y,c);
dfs(x,y-1,c);
dfs(x,y+1,c);
}
}
char other(char c) {
if (c=='B') return 'T';
if (c=='T') return 'B';
assert(false);
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin>>n>>m;
for (int i=0; i<n; i++) {
cin>>g[i];
}
dfs(0,0,g[0][0]);
while (qq.size()) {
cc++;
vector<pair<int,int>> cur = qq;
qq.clear();
char c = g[cur.back().first][cur.back().second];
for (auto p: cur) {
int x=p.first; int y=p.second;
for (auto mo: moves) {
int nx = mo.first+x;
int ny = mo.second+y;
if (nx>=0 && nx<n && ny>=0 && ny<m && !viz[nx][ny] && g[nx][ny]==other(c)) {
dfs(nx,ny,g[nx][ny]);
}
}
}
}
out(cc);
return 0;
}
