#include <bits/stdc++.h>
using namespace std;
long double PI = acos(-1);
long double DEL = 1e-10;
int M = 1e9 + 7;
const int N = 3e5 + 10;
#define ftt cin>>t;for(int tt=1;tt<=t;++tt)
#define all(a) a.begin(),a.end()
#define vpii vector<pair<int,int>>
#define vvi vector<vector<int>>
#define pii pair<int,int>
#define vi vector<int>
#define sq(a) ((a)*(a))
#define double long double
#define dbg cout<<"\nhi\n";
#define int long long
#define nl cout<<"\n"
#define sp <<" "<<
#define S second
#define F first
int fpow(int x, int n)
{
int res = 1;
x %= M;
while(n)
{
if(n&1)res = res * x % M;
x = x * x % M;
n>>=1;
}
return res;
}
int gcd(int a,int b)
{
if(b == 0)return a;
return gcd(b,a % b);
}
int lcm(int a,int b)
{
return a*(b/gcd(a,b));
}
void create_fac(int n)
{
vector<int> fac(N),inv(N);
fac[0] = inv[0] = 1;
for(int i=1;i<=n;i++)
{
fac[i] = fac[i-1]*i % M;
inv[i] = fpow(fac[i],M-2);
}
}
int ncr(int n,int r)
{
vector<int> fac(N),inv(N);
return fac[n] * (inv[r] * inv[n-r] % M) % M;
return fac[n] * (fpow(fac[r],M-2) * fpow(fac[n-r],M-2) % M ) % M;
}
void sieve (int n) // linear sieve
{
vector <int> primes;
bool iscomp[N];
for (int i = 2; i <= n; ++i)
{
if (!iscomp[i]) primes.push_back(i);
for (int j = 0; j < primes.size() && i * primes[j] <= n; ++j)
{
iscomp[i * primes[j]] = true;
if (i % primes[j] == 0) break;
}
}
}
// you can also use __int128
// priority_queue<int,vector<int>,greater<int>>
// bitset<100>(x).count()
//**************************************** CHECK CONSTRAINTS ***********************************************
int cnt, sum, mid, mx, mn, ans, a[N], b[N];
int n, m, d, i, j, k, l, p, q, r, t, w, x, y, z;
string s;
int32_t main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n >> m;
vvi a(n+2,vi(m+2)),dis(n+2,vi(m+2));
for(int i=1;i<=n;i++)for(int j=1;j<=m;j++)
{
char c;
cin>>c;
if(c == '.')
{
a[i][j] = 0;
}
else if(c == 'F')
{
a[i][j] = 2;
}
else
{
a[i][j] = 1;
}
}
dis[1][1] = 1;
deque<pii> q;
q.push_back({1,1});
while(!q.empty())
{
int i = q.front().F,j = q.front().S;
q.pop_front();
ans = max(ans,dis[i][j]);
if(!dis[i-1][j] and a[i-1][j])
{
if(a[i-1][j]!=a[i][j])
{
dis[i-1][j] = dis[i][j] + 1;
q.push_back({i-1,j});
}
else
{
dis[i-1][j] = dis[i][j];
q.push_front({i-1,j});
}
}
if(!dis[i+1][j] and a[i+1][j])
{
if(a[i+1][j]!=a[i][j])
{
dis[i+1][j] = dis[i][j] + 1;
q.push_back({i+1,j});
}
else
{
dis[i+1][j] = dis[i][j];
q.push_front({i+1,j});
}
}
//cout<<dis[i][j+1] sp a[i][j+1];nl;
if(!dis[i][j+1] and a[i][j+1])
{
if(a[i][j+1]!=a[i][j])
{
dis[i][j+1] = dis[i][j] + 1;
q.push_back({i,j+1});
}
else
{
dis[i][j+1] = dis[i][j];
q.push_front({i,j+1});
}
}
if(!dis[i][j-1] and a[i][j-1])
{
if(a[i][j-1]!=a[i][j])
{
dis[i][j-1] = dis[i][j] + 1;
q.push_back({i,j-1});
}
else
{
dis[i][j-1] = dis[i][j];
q.push_front({i,j-1});
}
}
}
cout<<ans;
}
/*
5 8
FFR.....
.FRRR...
.FFFFF..
..RRRFFR
.....FFF
*/
