#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
using pii = pair<int, int>;
const int MXN = 4005;
int n, m;
int A[MXN][MXN];
int dirI[] = {0, 0, -1, 1};
int dirJ[] = {-1, 1, 0, 0};
bool inbounds(int i, int j)
{
return i >= 0 && i < n && j >= 0 && j < m;
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
for(int i = 0; i < n; i++) {
for(int j = 0; j < m; j++) {
char c; cin >> c;
if(c == '.') A[i][j] = -1;
else if(c == 'F') A[i][j] = 0;
else A[i][j] = 1;
}
}
queue<pii> Q[2];
int which = A[0][0];
A[0][0] = -1;
Q[which].push({0, 0});
int cnt = 0;
do {
// for(int i = 0; i < n; i++) {
// for(int j = 0; j < m; j++) {
// cerr << setw(2) << A[i][j] << " ";
// }
// cerr << "\n";
// }
// cerr << "\n";
while(!Q[which].empty()) {
int i = Q[which].front().F, j = Q[which].front().S;
Q[which].pop();
for(int k = 0; k < 4; k++) {
int ii = i + dirI[k], jj = j + dirJ[k];
if(inbounds(ii, jj)) {
if(A[ii][jj] == which) {
A[ii][jj] = -1;
Q[which].push({ii, jj});
}
else if(A[ii][jj] == 1-which) {
A[ii][jj] = -1;
Q[1-which].push({ii, jj});
}
}
}
}
which = 1-which;
cnt++;
} while(!Q[which].empty());
cout << cnt;
return 0;
}
/*
5 8
FFR.....
.FRRR...
.FFFFF..
..RRRFFR
.....FFF
*/
