#include <bits/stdc++.h> using namespace std; using ll = long long; vector<ll> dx = {0, 1, 0, -1}; vector<ll> dy = {1, 0, -1, 0}; int main(){ ios::sync_with_stdio(false); cin.tie(nullptr); // freopen("template.in", "r", stdin); // freopen("template.out", "w", stdout); ll n, m; cin >> n >> m; vector<vector<ll>> snow(n + 2, vector<ll>(m + 2, -1)); for (ll i = 1; i <= n; ++i){ for (ll j = 1; j <= m; ++j){ char x; cin >> x; if (x == 'F'){ snow[i][j] = 1; } else if (x == 'R'){ snow[i][j] = 0; } } } vector<vector<ll>> d(n + 2, vector<ll>(m + 2, INT_MAX)); d[1][1] = 1; deque<pair<ll, ll>> dq; dq.push_back({1, 1}); ll maxd = 1; while (!dq.empty()){ auto p = dq.front(); dq.pop_front(); for (ll i = 0; i < 4; ++i){ pair<ll, ll> q = {p.first + dx[i], p.second + dy[i]}; if (snow[q.first][q.second] == -1){continue;} if (snow[q.first][q.second] == snow[p.first][p.second]){ if (d[p.first][p.second] < d[q.first][q.second]){ d[q.first][q.second] = d[p.first][p.second]; dq.push_front(q); } } else { if (d[p.first][p.second] + 1 < d[q.first][q.second]){ d[q.first][q.second] = d[p.first][p.second] + 1; dq.push_back(q); maxd = max(maxd, d[q.first][q.second]); } } } } cout << maxd; }