#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector,Ofast")
using namespace std;
typedef int ll;
typedef pair<ll,ll> pll;
#define X first
#define Y second
#define mp make_pair
#define REP1(i,n) for(int i=1;i<=n;i++)
const ll N=4e3+5;
string grid[N];
bool vis[N][N];
queue<pll> que;
ll n,m,ans;
ll dx[4]={-1,0,1,0},dy[4]={0,-1,0,1};
pll dest(pll now,ll dir){
return mp(now.X+dx[dir],now.Y+dy[dir]);
}
bool invalid(pll now){
return (now.X<=0||now.X>n||now.Y<=0||now.Y>m);
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);
cin>>n>>m;
REP1(i,n)cin>>grid[i],grid[i]='.'+grid[i]+'.';
que.push(mp(1,1));vis[1][1]=1;
que.push(mp(n,m));vis[n][m]=1;
for(char i=grid[1][1];;i=(i=='F'?'R':'F')){
vector<pll> nxt;
++ans;
while(!(que.empty())){
pll nd=que.front();que.pop();
for(int j=0;j<4;j++){
pll to=dest(nd,j);
if(vis[to.X][to.Y]||invalid(to))continue;
if(grid[to.X][to.Y]==i){
vis[to.X][to.Y]=1;
que.push(to);
}else if(grid[to.X][to.Y]!='.'){
vis[to.X][to.Y]=1;
nxt.push_back(to);
}
}
}
if((ll)nxt.size()==0)break;
for(pll j:nxt)que.push(j);
}
cout<<ans<<"\n";
return 0;
}
