#include <bits/stdc++.h>
using namespace std;
const int MAXN = 4e3+5;
int n, m, br = 0, ans = 0;
string a[MAXN];
void dfs(int i, int j){
if(i<0||j<0||i>=n||j>=m) return;
if(a[i][j]=='F'){
a[i][j] = '.';
}
else return;
dfs(i-1,j);
dfs(i+1,j);
dfs(i,j-1);
dfs(i,j+1);
}
void solve(){
cin >> n >> m;
for(int i = 0; i < n; ++i){
cin >> a[i];
}
if(a[0][0]=='R'){
for(int i = 0; i < n; ++i){
for(int j = 0; j < m; ++j){
if(a[i][j]=='R') a[i][j] = 'F';
else if(a[i][j]=='F') a[i][j] = 'R';
}
}
}
for(int i = 0; i < n; ++i){
for(int j = 0; j < m; ++j){
if(a[i][j]=='F'){
++ans;
++br;
dfs(i,j);
}
else if(a[i][j]=='.') ++br;
}
}
cout << min(ans,2)+(br!=n*m) << '\n';
}
int32_t main(){
ios_base::sync_with_stdio(0); cin.tie(0);
int32_t qqq=1;
//cin >> qqq;
while(qqq--)solve();
return 0;
}
