#include <bits/stdc++.h>
using namespace std;
char grid[5000][5000];
int visited[5000][5000];
vector<pair<int,int>> foxtrack, rabtrack;
void floodfill(vector<pair<int,int>> &track, int h, int w) {
pair<int,int> block;
while (track.size() > 0) {
block = track[track.size() - 1]; track.pop_back();
visited[block.first][block.second] = true;
//cout << block.first << ' ' << block.second << '\n';
if (block.first > 0) {
if (!visited[block.first - 1][block.second]) {
if (grid[block.first - 1][block.second] == 'F') {
foxtrack.push_back(make_pair(block.first - 1, block.second));
} else if (grid[block.first - 1][block.second] == 'R') {
rabtrack.push_back(make_pair(block.first - 1, block.second));
}
}
}
if (block.first < h - 1) {
if (!visited[block.first + 1][block.second]) {
if (grid[block.first + 1][block.second] == 'F') {
foxtrack.push_back(make_pair(block.first + 1, block.second));
} else if (grid[block.first + 1][block.second] == 'R') {
rabtrack.push_back(make_pair(block.first + 1, block.second));
}
}
}
if (block.second > 0) {
if (!visited[block.first][block.second - 1]) {
if (grid[block.first][block.second - 1] == 'F') {
foxtrack.push_back(make_pair(block.first, block.second - 1));
} else if (grid[block.first][block.second - 1] == 'R') {
rabtrack.push_back(make_pair(block.first, block.second - 1));
}
}
}
if (block.second < w - 1) {
if (!visited[block.first][block.second + 1]) {
if (grid[block.first][block.second + 1] == 'F') {
foxtrack.push_back(make_pair(block.first, block.second + 1));
} else if (grid[block.first][block.second + 1] == 'R') {
rabtrack.push_back(make_pair(block.first, block.second + 1));
}
}
}
}
}
int main() {
int h, w; cin >> h >> w;
for (int i=0;i<h;i++) {
for (int j=0;j<w;j++) {
cin >> grid[i][j];
visited[i][j] = false;
}
}
char animal = grid[0][0];
int ans = 0;
pair<int,int> block;
if (grid[0][0] == 'F') {
foxtrack.push_back(make_pair(0, 0));
} else {
rabtrack.push_back(make_pair(0, 0));
}
while (true) {
if (animal == 'F') {
if (foxtrack.size() == 0) {
break;
}
floodfill(foxtrack, h, w);
animal = 'R';
} else {
if (rabtrack.size() == 0) {
break;
}
floodfill(rabtrack, h, w);
animal = 'F';
}
ans++;
}
cout << ans;
}
