// #include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <vector>
#include <iomanip>
#include <string>
#include <queue>
#include <set>
#include <deque>
using namespace std;
#define int long long
#define endl "\n"
#define fi first
#define se second
const int M=1e9+7;
const int inf = 1e14;
const int LOG=18;
const int N=4e3+5;
int n , m , c , w , k , t=1 , q=1 , x , y , z , l , r;
int vi[N][N];
void solve(){
cin >> n >> m;
string s;
for (int i=0;i<m+2;i++){
s+='.';
}
vector<string>a(n+2);
a[0]=a[m+1]=s;
for (int i=1;i<=n;i++){
cin >> a[i];
a[i]='.'+a[i];
a[i]+='.';
}
for (int i=0;i<n+2;i++){
vi[i][0]=1;
vi[i][m+1]=1;
}
for (int i=0;i<m+2;i++){
vi[0][i]=1;
vi[n+1][i]=1;
}
k=0;
for (int i=1;i<=n;i++){
for (int j=1;j<=m;j++){
k+=(a[i][j]!='.');
}
}
c=0;
int vs=0;
vector<pair<int,int>>hl;
hl.push_back({1,1});
queue<pair<int,int>>o;
char p=a[1][1];
vector<pair<int,int>>lk;
lk.push_back({1,0});
lk.push_back({-1,0});
lk.push_back({0,1});
lk.push_back({0,-1});
while (vs<k){
for (auto i:hl){
o.push(i);
if (!vi[i.fi][i.se]){
vs++;
vi[i.fi][i.se]=1;
}
}
hl.clear();
while (o.size()){
auto h=o.front();
o.pop();
int i=h.fi;
int j=h.se;
for (auto [x,y]:lk){
if (vi[i+x][j+y])continue;
if (a[i+x][j+y]==p){
vs++;
o.push({i+x,j+y});
// cout << i+x << " " << j+y << endl;
vi[i+x][j+y]=1;
}
else if(a[i+x][j+y]=='.'){
vi[i+x][j+y]=1;
}
else if(hl.empty() or hl[hl.size()-1]!=make_pair(i,j)){
hl.push_back({i,j});
}
}
}
if (p=='R'){
p='F';
}
else{
p='R';
}
c++;
// cout << endl;
// for (auto i:hl){
// cout << i.fi << " " << i.se << endl;
// }
// cout << vs;
// cout << endl;
}
cout << c << endl;
}
signed main()
{
ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE
cin.tie(0), cout.tie(0);//DO NOT USE IN INTERACTIVE
cout << fixed << setprecision(9);
srand(time(0));
// int t=1;
// cin >> t;
for (int _=1;_<=t;_++){
solve();
q++;
}
}
