#include <iostream>
#include <vector>
#include <map>
#include <cmath>
#include <algorithm>
#include <deque>
#include <queue>
#include <stack>
#include <set>
#include <string>
#include <string.h>
#include <array>
#include <unordered_map>
#include <unordered_set>
#include <iomanip>
using namespace std;
typedef long long ll;
const int MaxN = 4e3;
int h, w, prevsize = 0;
char arr[MaxN][MaxN];
bool dfs(char type) {
queue<pair<int, int>> q;
q.push({0,0});
int count=0;
while (!q.empty()) {
pair<int, int> cur = q.front();
q.pop();
if (cur.first < 0 || cur.second < 0 || cur.first >= h || cur.second >= w) continue;
if (arr[cur.first][cur.second] != type) continue;
count++;
if (type == 'F') arr[cur.first][cur.second] = 'R';
else arr[cur.first][cur.second] = 'F';
q.push({cur.first+1, cur.second});
q.push({cur.first-1, cur.second});
q.push({cur.first, cur.second+1});
q.push({cur.first, cur.second-1});
}
bool works = count != prevsize;
prevsize = count;
return works;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> h >> w;
for (int i=0; i<h; i++) {
for (int j=0; j<w; j++) {
cin >> arr[i][j];
}
}
bool fox = false;
if (arr[0][0] == 'F') fox = true;
int count=0;
while (true) {
char type = 'F';
if (!fox) type = 'R';
if (!dfs(type)) break;
count++;
fox = !fox;
}
cout << count;
}
