#include <bits/stdc++.h>
#include <utility>
using namespace std;
using ll = long long;
using ld = long double;
#define f first
#define s second
#define mod(a, b) (((a)%(b)+(b))%(b))
#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template <class T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,
tree_order_statistics_node_update>;
const ll MAX_N = 1e5 + 5;
const ll MOD = 1e9+7;
const ll dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
void setio(string s="") {
ios::sync_with_stdio(false);
cin.tie(nullptr);
if (size(s)) {
freopen((s+".in").c_str(),"r",stdin);
freopen((s+".out").c_str(),"w",stdout);
}
}
#ifdef LOCAL
#include "debug.h"
#endif
void solve() {
ll n,m; cin >> n >> m;
vector<vector<ll>> v(n,vector<ll>(m));
for (auto &i : v) {
for (auto &j : i) {
char c; cin >> c;
if (c=='.') j=2;
else j=(c=='F');
}
}
deque<pair<ll,pair<ll,ll>>> q;
q.push_front({0,{0,0}});
ll ans=0;
vector<vector<ll>> dist(n,vector<ll>(m,1e18));
dist[0][0]=0;
while (!q.empty()) {
auto [w,p]=q.front(); q.pop_front();
ll r=p.f, c=p.s;
if (dist[r][c]!=w) continue;
chmax(ans,w);
auto ad = [&](ll dr, ll dc, ll w) {
ll nr=r+dr, nc=c+dc;
if (nr<0 || nr>=n || nc<0 || nc>=m || v[nr][nc]==2) return;
ll nw=w;
nw += v[r][c]^v[nr][c];
nw += v[r][c]^v[r][nc];
if (dist[nr][nc]>nw) {
dist[nr][nc]=nw;
if (nw-w) q.push_back({nw,{nr,nc}});
else q.push_front({nw,{nr,nc}});
}
};
for (ll i=0; i<4; ++i) {
ad(dy[i],dx[i],w);
}
}
cout << ans+1 << '\n';
}
signed main() {
setio();
ll tc = 1;
// cin >> tc;
while (tc--) {
// cout << "tc 1:\n";
solve();
}
}
