#pragma GCC optimize ("O1")
#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define pb push_back
#define F first
#define S second
#define ll long long
#define int ll
#define pii pair<int, int>
#define io ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define M_PI 3.14159265358979323846
#define all(v) v.begin(), v.end()
#define pss pair<string, string>
#define no cout<<"NO"<<endl;
#define yes cout<<"YES"<<endl;
#define imp cout<<-1<<endl;
#define flu cout.flush();
#define Endl endl
const int N = 100009;
const int mod = 1e9+7;
int a[4005][4005];
int used[4005][4005];
int dx[]={1, -1, 0, 0, 1, -1, 1, -1};
int dy[]={0, 0, -1, 1, 1, -1, -1, 1};
int n, m;
int start, ans=1, cnt=0;
vector<pii>ne;
queue<pii>q;
void bfs(){
while(!q.empty()){
int x=q.front().F, y=q.front().S;
q.pop();
/*cout<<x<<" "<<y<<endl;
cnt++;
if(cnt>50){
exit(0);
}*/
if(used[x][y]!=0){
continue;
}
used[x][y]++;
for(int i=0; i<4; i++){
int xx=dx[i]+x, yy=dy[i]+y;
if(xx>=n or xx<0){
continue;
}
if(yy>=m or yy<0){
continue;
}
if(used[xx][yy]==0 and a[xx][yy]==start){
q.push({xx, yy});
}
if(used[xx][yy]==0 and a[xx][yy]==(-1)*start){
ne.pb({xx, yy});
}
}
}
if(ne.size()!=0){
ans++;
start*=(-1);
for(pii i : ne){
q.push({i.F, i.S});
}
ne.clear();
bfs();
}
}
void solve(){
cin>>n>>m;
for(int i=0; i<n; i++){
for(int j=0; j<m; j++){
char c;
cin>>c;
if(c=='F'){
a[i][j]=1;
}
else if(c=='R'){
a[i][j]=-1;
}
}
}
start=a[0][0];
q.push({0, 0});
bfs();
cout<<ans<<endl;
/*
FRFF
FRRR
FFFF
FFRFFFFF
FFRRRFFF
FFFFFFFF
FFRRRFFR
FFFFFFFF
*/
}
signed main(){
//io;
int t=1;
//cin>>t;
while(t--){
solve();
}
}
