#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main() {
int n, m;
cin >> n >> m;
int r=0,f=0;
vector<vector<char> > g(n, vector<char>(m));
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
cin >> g[i][j];
if(g[i][j]=='R')
{r++;
}
else if(g[i][j]=='F')
{f++;
}
}
}
// Define direction vectors for 4 directions
// vector<pair<int, int> > v = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
vector<pair<int,int > >v;
v.push_back({-1,0});
v.push_back({0,-1});
v.push_back({0,1});
v.push_back({1,0});
// Initialize the level array
vector<vector<int> > level(n, vector<int>(m, LLONG_MAX));
level[0][0] = 0;
// BFS queue
queue<pair<int, int> > q;
q.push({0, 0});
while (!q.empty()) {
pair<int, int> p = q.front();
q.pop();
for (int i = 0; i < 4; i++) {
int d = p.first + v[i].first;
int e = p.second + v[i].second;
// Boundary check
if (d >= 0 && d < n && e >= 0 && e < m && g[d][e]!='.') {
int wt = (g[p.first][p.second] != g[d][e]) ? 1 : 0;
if (wt + level[p.first][p.second] < level[d][e]) {
level[d][e] = wt + level[p.first][p.second];
q.push({d, e}); // Push valid neighbor
}
}
}
}
//if(level[n-1][m-1]==0)
//{
// level[n-1][m-1]=(f!=0)+(r!=0);
//}
// // Output the shortest path weight to the bottom-right corner
cout << level[n-1][m-1] +(f!=0)+(r!=0)<< endl;
return 0;
}
