#include <bits/stdc++.h>
using namespace std;
#define BOTH 3
#define FOX 2
#define RAB 1
#define NONE 0
bool ff(vector<vector<int>> &map, int type, int N, int M) {
bool cont = false;
vector<vector<bool>> vis(N, vector<bool>(M, false)); vis[0][0] = true;
queue<vector<int>> q;
q.push({0, 0});
while (!q.empty()) {
vector<int> p = q.front(); q.pop();
vis[p[0]][p[1]] = true;
if (map[p[0]][p[1]] != BOTH) cont = true;
map[p[0]][p[1]] = BOTH;
if (p[0] > 0 && !vis[p[0]-1][p[1]] && (type & map[p[0]-1][p[1]])) q.push({p[0] - 1, p[1]});
if (p[1] > 0 && !vis[p[0]][p[1]-1] && (type & map[p[0]][p[1]-1])) q.push({p[0], p[1] - 1});
if (p[0] < N-1 && !vis[p[0]+1][p[1]] && (type & map[p[0]+1][p[1]])) q.push({p[0] + 1, p[1]});
if (p[1] < M-1 && !vis[p[0]][p[1]+1] && (type & map[p[0]][p[1]+1])) q.push({p[0], p[1] + 1});
}
return cont;
}
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);
}
}
if (!map[0][0]) {cout << 0; return 0;}
bool cont = true;
int type = map[0][0] == FOX ? FOX : RAB;
int a = 0;
while (cont) {
cont = ff(map, type, N, M);
type ^= 3; // switches
if (cont) a++;
}
cout << a;
}
