#include <bits/stdc++.h>
#define fr(i, n, m) for(int i = (n); i < (m); i ++)
#define pb push_back
#define st first
#define nd second
#define pq priority_queue
#define all(x) begin(x),end(x)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
ll const inf = 1e9;
ll const mod = 1e9 + 7;
ld const eps = 1e-9;
int const red = 0;
int const green = 1;
int const neu = 2;
int const black = 3;
int n, m;
int a[4003][4003];
bool vis[4003][4003];
int dr[4] = {1, -1, 0, 0};
int dc[4] = {0, 0, 1,-1};
int col;
bool ok(int r, int c, int i){
if(r + dr[i] < n && r + dr[i] >= 0 && c + dc[i] < m && c + dc[i] >= 0 && !vis[r + dr[i]][c + dc[i]] && (a[r + dr[i]][c + dc[i]] == col || a[r + dr[i]][c + dc[i]] == neu)){
return true;
}
else return false;
}
int cnt = 0;
void floodfill(int r, int c){
fr(i, 0, 4){
if(ok(r, c, i)){
vis[r + dr[i]][c + dc[i]] = true;
a[r + dr[i]][c + dc[i]] = neu;
cnt ++;
floodfill(r + dr[i],c + dc[i]);
}
}
}
int main()
{
cin >> n >> m;
int all = n * m;
fr(i, 0, n){
fr(j, 0, m){
char c;
cin >> c;
if(c == 'R') a[i][j] = red;
else if(c == 'F') a[i][j] = green;
else{
a[i][j] = black;
all --;
}
}
}
col = a[0][0];
int ziv = 0;
cnt = 0;
while(cnt != all){
a[0][0] = col;
memset(vis, false, sizeof(vis));
cnt = 1;
vis[0][0] = true;
floodfill(0, 0);
col ^= 1;
ziv ++;
}
cout << ziv << endl;
return 0;
}
