// #pragma GCC target ("avx,avx2,fma")
#pragma GCC optimize ("Ofast,inline") // O1 - O2 - O3 - Os - Ofast
// #pragma GCC optimize ("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define rep(i, a, b) for (int i = (a); i < (b); ++i)
#define per(i, a, b) for (int i = (b - 1); i >= (a); --i)
#define trav(a, x) for (auto &a : x)
#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back
#define debug(x) cout << #x << " = " << x << endl
#define umap unordered_map
#define uset unordered_set
typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<pll> vpll;
const int INF = 1'000'000'007;
int dr[] = {1, -1, 0, 0};
int dc[] = {0, 0, -1, 1};
bitset<4001> visited[4001], taken[4001];
string grid[4001];
int rows, cols, ans = 0;
char cur_animal;
bool valid(int row, int col) { return 0 <= row && row < rows && 0 <= col && col < cols; }
int main() {
cin.tie(0)->sync_with_stdio(0);
cin.exceptions(cin.failbit);
cin >> rows >> cols;
rep(i, 0, rows) cin >> grid[i];
cur_animal = grid[0][0];
queue<ii> q;
visited[0][0] = 1;
q.emplace(0, 0);
while (!q.empty()) {
queue<ii> nxtq;
while (!q.empty()) {
int row, col;
tie(row, col) = q.front();
q.pop();
rep(i, 0, 4) {
int nr = row + dr[i], nc = col + dc[i];
if (valid(nr, nc)) {
if (!visited[nr][nc] && grid[nr][nc] == cur_animal) {
q.emplace(nr, nc);
visited[nr][nc] = 1;
}
if (!visited[nr][nc] && grid[nr][nc] != cur_animal && grid[nr][nc] != '.') {
visited[nr][nc] = 1;
nxtq.emplace(nr, nc);
}
}
}
}
if (cur_animal == 'F')
cur_animal = 'R';
else
cur_animal = 'F';
q.swap(nxtq);
++ans;
}
cout << ans << endl;
return 0;
}
