#include <bits/stdc++.h>
using namespace std;
using ll = long long;
vector<int> X = {-1, 0, 1, 0}, Y = {0, 1, 0, -1};
int main() {
ios::sync_with_stdio(false); cin.tie(nullptr);
int n, m;
cin >> n >> m;
vector<string> a(n);
for (auto &i : a)
cin >> i;
char c = a[0][0];
vector<vector<bool>> mp(n, vector<bool>(m)); mp[0][0] = true;
for (int z = 0; ; z++) {
bool tr = !z;
queue<pair<int, int>> q;
vector<vector<bool>> vis(n, vector<bool>(m));
q.push({0, 0}); vis[0][0] = true;
while (!q.empty()) {
auto [x, y] = q.front(); q.pop();
for (int i = 0; i < 4; i++) {
int nx = x + X[i], ny = y + Y[i];
if (0 <= min(nx, ny) && nx < n && ny < m && !vis[nx][ny] && (mp[nx][ny] || c == a[nx][ny])) {
q.push({nx, ny});
tr |= !mp[nx][ny];
vis[nx][ny] = mp[nx][ny] = true;
}
}
}
c = (c == 'F' ? 'R' : 'F');
if (!tr) return cout << z, 0;
}
}
