#include <bits/stdc++.h>
using namespace std;
char grid[4000][4000];
int h, w;
vector<pair<int, int>> border;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> h >> w;
for (int i=0; i<h; i++) {
for (int j=0; j<w; j++) {
cin >> grid[i][j];
}
}
border.push_back({0, 0});
char animal = grid[0][0];
char other = ((animal == 'R') ? 'F' : 'R');
int ans = 0;
while (!border.empty()) {
ans++;
queue<pair<int, int>> q;
while (!border.empty()) {
q.push(border.back());
border.pop_back();
}
while (!q.empty()) {
pair<int, int> curr = q.front(); q.pop();
if (grid[curr.first][curr.second] != animal) {
if (grid[curr.first][curr.second] == other) {
border.push_back(curr);
}
continue;
}
grid[curr.first][curr.second] = '*';
if (curr.first > 0) q.emplace((pair<int, int>){curr.first - 1, curr.second});
if (curr.first < h - 1) q.emplace((pair<int, int>){curr.first + 1, curr.second});
if (curr.second > 0) q.emplace((pair<int, int>){curr.first, curr.second - 1});
if (curr.second < w - 1) q.emplace((pair<int, int>){curr.first, curr.second + 1});
}
tie(animal, other) = make_tuple(other, animal);
}
cout << ans << "\n";
}
