#include <bits/stdc++.h>
using namespace std;
#define int long long
vector<pair<int, int>> dir;
void solve(){
int h, w; cin >> h >> w;
vector<vector<char>> v(h, vector<char>(w, '.'));
for (int i = 0; i < h; i ++){
for (int j = 0; j < w; j ++){
cin >> v[i][j];
}
}
bool fox = false;
if (v[0][0] == 'F') fox = true;
auto check = [&](int i, int j) -> bool {
if (i >= 0 && i < h && j >= 0 && j < w && v[i][j] != '.') return true;
else return false;
};
vector<vector<bool>> visited(h, vector<bool>(w, false));
queue<pair<int, int>> q;
q.push({0,0}); visited[0][0] = true;
int ans = 1;
queue<pair<int, int>> real;
while (!q.empty()){
pair<int, int> oh = q.front();
real.push(oh);
q.pop();
for (auto w : dir){
if (!check(w.first + oh.first, w.second + oh.second)) continue;
else if (visited[w.first + oh.first][w.second + oh.second]) continue;
else if (fox && v[w.first + oh.first][w.second + oh.second] == 'R') continue;
else if (!fox && v[w.first + oh.first][w.second + oh.second] == 'F') continue;
visited[w.first + oh.first][w.second + oh.second] = true;
q.push({w.first + oh.first, w.second + oh.second});
}
}
// at this point fox only tells me the state of shit in the queue
while (!real.empty()){
pair<int, int> oh = real.front();
if ((fox && v[oh.first][oh.second] == 'R') || (!fox && v[oh.first][oh.second] == 'F')) {fox = !fox; ans ++;}
real.pop();
for (auto w : dir){
int x = w.first + oh.first; int y = w.second + oh.second;
if (!check(x, y)) continue;
else if (visited[x][y]) continue;
visited[x][y] = true;
real.push({x,y});
}
}
cout << ans << '\n';
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int t = 1;
// cin >> t;
dir.push_back({0,1}); dir.push_back({-1,0}); dir.push_back({1,0}); dir.push_back({0,-1});
while (t --){
solve();
}
return 0;
}
