#include <bits/stdc++.h>
using namespace std;
#undef _GLIBCXX_DEBUG
#define rep(i, a, b) for(ll i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef pair<ll, ll> pll;
typedef vector<ll> vl;
vector<vector<char>> grid;
bool visited[4010][4010];
ll H, W;
vector<pair<ll,ll>> q;
vector<pair<ll,ll>> q2;
ll dfs(ll row, ll col, char curr){
if (row >= H || col >= W || col < 0 || row <0) return 0;
if (visited[row][col] == 1) return 0;
if (grid[row][col] =='.') return 0;
if (grid[row][col] != curr){
q2.push_back(make_pair(row,col));
//cout << "in bfs " << row << " " << col << "\n";
return 0;
}
visited[row][col] = 1;
dfs(row+1, col,curr);
dfs(row-1, col,curr);
dfs(row, col+1,curr);
dfs(row, col-1,curr);
return 0;
}
int main(){
//cin.tie(0)->sync_with_stdio(0);
memset(visited, 0, sizeof(visited));
cin >>H >> W;
grid.resize(H, vector<char>(W));
char temp;
rep(i,0,H)
rep (j,0,W){
cin >> temp;
grid[i][j] = temp;
}
char ani = grid[0][0];
q.push_back(make_pair(0,0));
ll cnt =0;
while (q.size()){
while(!q.empty()){
pll s = q.back();
q.pop_back();
dfs(s.first, s.second, grid[s.first][s.second]);
}
//cout << "new q " << "\n";
cnt ++;
swap(q, q2);
q2.clear();
if (ani == 'R') ani = 'F';
if (ani == 'F') ani = 'R';
}
cout << cnt << "\n";
return 0;
}
