#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main() {
int n, m;
cin >> n >> m;
int r = 0, f = 0;
vector<vector<char> > g(n, vector<char>(m));
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
cin >> g[i][j];
if (g[i][j] == 'R') {
r++;
} else if (g[i][j] == 'F') {
f++;
}
}
}
// Define direction vectors for 4 directions
vector<pair<int,int > >v;
v.push_back({-1,0});
v.push_back({0,-1});
v.push_back({0,1});
v.push_back({1,0});
// Initialize the level array
vector<vector<int> > level(n, vector<int>(m, LLONG_MAX));
level[0][0] = 0;
// 0/1 BFS using deque
deque<pair<int, int> > dq;
dq.push_front({0, 0});
while (!dq.empty()) {
pair<int, int> p = dq.front();
dq.pop_front();
for (int i = 0; i < 4; i++) {
int d = p.first + v[i].first;
int e = p.second + v[i].second;
// Boundary check
if (d >= 0 && d < n && e >= 0 && e < m && g[d][e] != '.') {
int wt = (g[p.first][p.second] != g[d][e]) ? 1 : 0;
if (wt + level[p.first][p.second] < level[d][e]) {
level[d][e] = wt + level[p.first][p.second];
if (wt == 1) {
dq.push_back({d, e}); // Push to the back if weight is 1
} else {
dq.push_front({d, e}); // Push to the front if weight is 0
}
}
}
}
}
// Adjust result for corner cases
int result = level[n-1][m-1];
if (result == LLONG_MAX) {
cout << -1 << endl; // If destination is unreachable
} else {
cout << result + (f != 0) + (r != 0) << endl; // Include additional penalties if required
}
return 0;
}
