#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
#define fi first
#define se second
#define pb push_back
#define all(x) x.begin(), x.end()
#define MOD 1000000007
const int MAXN=4e3+1;
int vis[MAXN][MAXN];
int grid[MAXN][MAXN];
int h,w;
int xyon[5]={1,0,-1,0};
int yyon[5]={0,-1,0,1};
int say=0;
bool isvalid(int x,int y,int deg){
if(x>=h or x<0 or y>=w or y<0) return false;
if(grid[x][y]==-1) return false;
if(grid[x][y]!=deg) return false;
return true;
}
void bfs(int x,int y){
queue<pii> q;
q.push({x,y});
vis[x][y]=true;
say++;
int deg=grid[x][y];
grid[x][y]=!deg;
while(!q.empty()){
auto el=q.front();
q.pop();
for(int i=0;i<4;i++){
int newx=el.fi+xyon[i];
int newy=el.se+yyon[i];
if(isvalid(newx,newy,deg) and !vis[newx][newy]){
//cout<<grid[el.fi][el.se]<<"-->"<<grid[newx][newy]<<endl;
vis[newx][newy]=true;
q.push({newx,newy});
grid[newx][newy]=!deg;
say++;
}
}
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
//ifstream cin("lepus.in");
//ofstream cout("lepus.out");
cin>>h>>w;
map<char,int> anim;
anim['F']=1;
anim['R']=0;
anim['.']=-1;
int all_steps=0;
for(int i=0;i<h;i++){
for(int j=0;j<w;j++){
char c;
cin>>c;
grid[i][j]=anim[c];
if(grid[i][j]!=-1){
all_steps++;
}
}
}
//cout<<all_steps<<endl;
int cev=0;
while(all_steps!=say){
say=0;
bfs(0,0);
//cout<<"s: "<<say<<endl;
for(int i=0;i<h;i++){
for(int j=0;j<w;j++){
vis[i][j]=false;
}
}
cev++;
}
cout<<cev<<endl;
/*for(int i=0;i<h;i++){
for(int j=0;j<w;j++){
cout<<grid[i][j]<<' ';
}
cout<<endl;
}*/
}
