#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double ld;
#define pb push_back
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define F first
#define S second
const int N = 4000;
int n, m, ans = 1;
char c[N][N];
bool fc[N][N];
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};
vector<pair<int, int>> f, r;
bool vis[N][N];
void dfs(int i, int j) {
fc[i][j] = true;
if(vis[i][j])return;
vis[i][j] = true;
for (int ii = 0; ii < 4; ii++) {
int nx = i + dx[ii], ny = j + dy[ii];
if (nx < 0 || ny < 0 || nx >= n || ny >= m)continue;
if (c[nx][ny] == c[0][0]) {
if (!fc[nx][ny])dfs(nx, ny);
} else if (!vis[nx][ny]) {
if (c[nx][ny] == 'F')f.pb({nx, ny});
else if (c[nx][ny] == 'R')r.pb({nx, ny});
vis[nx][ny] = true;
}
}
}
int main () {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> m;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
cin >> c[i][j];
}
}
dfs(0, 0);
char cur = 'R';
if (c[0][0] == cur)cur = 'F';
while (!f.empty() || !r.empty()) {
if (cur == 'R') {
if (!r.empty())ans++;
while (!r.empty()) {
int x = r.back().F, y = r.back().S;
r.pop_back();
for (int i = 0; i < 4; i++) {
int nx = x + dx[i], ny = y + dy[i];
if (nx < 0 || ny < 0 || nx >= n || ny >= m)continue;
if (vis[nx][ny])continue;
vis[nx][ny] = true;
if (c[nx][ny] == 'R')r.pb({nx, ny});
else if (c[nx][ny] == 'F')f.pb({nx, ny});
}
}
} else {
if (!f.empty()) {
ans++;
}
while (!f.empty()) {
int x = f.back().F, y = f.back().S;
f.pop_back();
for (int i = 0; i < 4; i++) {
int nx = x + dx[i], ny = y + dy[i];
if (nx < 0 || ny < 0 || nx >= n || ny >= m)continue;
if (vis[nx][ny])continue;
vis[nx][ny] = true;
if (c[nx][ny] == 'R')r.pb({nx, ny});
else if (c[nx][ny] == 'F')f.pb({nx, ny});
}
}
}
if (cur == 'F')cur = 'R';
else cur = 'F';
}
cout << ans;
}
