#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)
{
if (vis[i][j] || fc[i][j])
return;
fc[i][j] = true;
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] && !vis[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;
}
