#include <bits/stdc++.h>
using namespace std;
#define endl "\n"
#define pb push_back
#define int long long
#define fi first
#define se second
const int N = 4e3 + 5, M = 1e9 + 7, LG = 20;
int n , A[N] , L[4] = {0,0,1,-1} , R[4] = {1,-1,0,0} , ans , m;
bool vi[N][N];
char gr[N][N];
bool ch(int x , int y){
if (1 <= x && x <= n && 1 <= y && y <= m) return 1;
return 0;
}
void solve(){
cin >> n >> m;
for (int i=1 ; i<=n ; i++){
for (int j=1 ; j<=m ; j++){
cin >> gr[i][j];
}
}
queue<pair<int,int>> s , t;
s.push({1,1});
char c = gr[1][1];
while(1){
bool sm = 0;
while(s.size()){
sm = 1;
int x = s.front().fi , y = s.front().se ; s.pop();
if (vi[x][y]) continue;
vi[x][y] = 1;
for (int i=0 ; i<4 ; i++){
int nx = x+L[i] , ny = y+R[i];
if (!ch(nx,ny) || vi[nx][ny]) continue;
if (gr[nx][ny] == '.') continue;
if (gr[nx][ny] == c){
s.push({nx,ny});
}else{
t.push({nx,ny});
}
}
}
if (!sm) break;
ans++;
while(t.size()){
s.push(t.front());
t.pop();
}
if (c == 'F') c = 'R';
else c = 'F';
}
cout << ans << endl;
}
signed main(){
// freopen("" , "r" , stdin);
// freopen("" , "w" , stdout);
// cout << setprecision(30);
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int ts = 1;
// cin >> ts;
while(ts--){
solve();
}
}
