#include "bits/stdc++.h"
using namespace std;
#define all(x) x.begin(), x.end()
#define pb(x) push_back(x)
#define endl '\n'
#define sz(x) (int)x.size()
#define mr(x, y) make_pair(x, y)
#define F first
#define S second
#define pii pair<int, int>
const int N = 4e3 + 10;
const int MOD = 1e9 + 7;
char c[N][N];
pair<int, int> par[N][N];
set<pii> pars;
vector<pair<int, int>> vec[N][N];
int dx[4] = {0, 0, 1, -1}, dy[4] = {1, -1, 0, 0}, n, m;
pii nxt;
string s[10];
void merge(pair<int, int> u, pair<int, int> v){
if(par[u.F][u.S] == par[v.F][v.S])
return;
u = par[u.F][u.S], v = par[v.F][v.S];
if(sz(vec[u.F][u.S]) > sz(vec[v.F][v.S]))
swap(u, v);
pars.erase(u);
for(pair<int, int> y : vec[u.F][u.S]){
par[y.F][y.S] = v;
vec[v.F][v.S].pb(y);
}
vec[u.F][u.S].clear();
}
void upd(pair<int, int> v){
c[v.F][v.S] = 'O';
pars.erase(v);
vector<pair<int, int>> r, f;
for(pair<int, int> y : vec[v.F][v.S]){
int i = y.F, j = y.S;
for(int k = 0; k < 4; k++){
if(i + dx[k] > 0 && i + dx[k] <= n && j + dy[k] > 0 && j + dy[k] <= m){
pii t = par[i + dx[k]][j + dy[k]];
if(c[t.F][t.S] == 'O' || c[t.F][t.S] == '.')
continue;
//cout << i + dx[k] << " " << j + dy[k] << endl;
if(c[i + dx[k]][j + dy[k]] == 'R')
r.pb(mr(i + dx[k], j + dy[k]));
else if(c[i + dx[k]][j + dy[k]] == 'F')
f.pb(mr(i + dx[k], j + dy[k]));
}
}
}
//exit(0);
for(int i = 1; i < sz(r); i++)
merge(r[i], r[i - 1]);
for(int i = 1; i < sz(f); i++)
merge(f[i], f[i - 1]);
if(sz(r) == 0 && sz(f) == 0)
nxt = mr(-1, -1);
else if(sz(r) == 0)
nxt = par[f[0].F][f[0].S];
else
nxt = par[r[0].F][r[0].S];
}
int main(){
ios_base :: sync_with_stdio(0), cin.tie(0), cout.tie(0);
cin >> n >> m;
/* n = 5, m = 8;
s[1] = "!FFR.....";
s[2] = "!.FRRR...";
s[3] = "!.FFFFF..";
s[4] = "!..RRRFFR";
s[5] = "!.....FFF";*/
for(int i = 1; i <= n; i++){
for(int j = 1; j <= m; j++){
cin >> c[i][j];
//c[i][j] = s[i][j];
if(c[i][j] == '.')
continue;
pars.insert(mr(i, j));
par[i][j] = mr(i, j);
vec[i][j].pb(mr(i, j));
}
}
for(int i = 1; i <= n; i++){
for(int j = 1; j <= m; j++){
for(int k = 0; k < 4; k++){
if(i + dx[k] > 0 && i + dx[k] <= n && j + dy[k] > 0 && j + dy[k] <= m){
if(c[i][j] != '.' && c[i][j] == c[i + dx[k]][j + dy[k]])
merge(mr(i, j), mr(i + dx[k], j + dy[k]));
}
}
}
}
int ans = 1;
upd(par[1][1]);
while(!pars.empty()){
upd(nxt);
ans++;
}
cout << ans;
}
