#include <bits/stdc++.h>
using namespace std;
#define BOTH 3
#define FOX 2
#define RAB 1
#define NONE 0
int main() {
int N, M;
cin >> N >> M;
vector<vector<int>> map(N, vector<int>(M, 0));
for (int i = 0; i < N; i++) {
for (int j = 0; j < M; j++) {
char c;
cin >> c;
map[i][j] = c == 'F' ? FOX : (c == 'R' ? RAB : NONE);
}
}
queue<pair<int,int>> q;
q.push({0, 0});
queue<pair<int,int>> newQ;
vector<vector<bool>> vis(N, vector<bool>(M, false));
vis[0][0] = true;
vector<int> xs = {0, 1, 0, -1};
vector<int> ys = {1, 0, -1, 0};
bool cont = true;
int l = 0;
while (!q.empty()) {
while (!q.empty()) {
pair<int,int> v = q.front();
q.pop();
for (int dir = 0; dir < 4; dir++) {
int x = v.first + xs[dir];
int y = v.second + ys[dir];
if (x < 0 || x >= N || y < 0 || y >= M) continue;
if (vis[x][y]) continue;
if (map[x][y] == NONE) continue;
if (map[x][y] == map[v.first][v.second]) {
q.push({x, y});
vis[x][y] = true;
} else {
newQ.push({x, y});
vis[x][y] = true;
}
}
}
q = newQ;
queue<pair<int, int>> empty;
newQ = empty;
l++;
}
cout << (map[0][0] != NONE ? l : 0);
}
