#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define run ios_base::sync_with_stdio(false);cin.tie(0);
#define ll int
#define pll pair<ll, ll>
#define ull unsigned ll
#define ld double
#define endl "\n"
#define pb push_back
#define fi first
#define se second
#define pi acos(-1)
#define N 4007
#define minimum -9223372036854775807
#define maximum -minimum
#define mod 1000000007
using namespace std;
using namespace __gnu_pbds;
template <class t>
using ordered_set=tree<t, null_type,less_equal<t>, rb_tree_tag,tree_order_statistics_node_update>;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll gcd(ll a, ll b)
{
if(b==0)
return a;
return gcd(b, a%b);
}
ll lcm(ll a, ll b)
{
return a/gcd(a, b)*b;
}
bool isprime(ll n)
{
if(n==1)
return 0;
for(ll i=2; i*i<=n; i++)
{
if(n%i==0)
return 0;
}
return 1;
}
ll binpow(ll a, ll b)
{
a%=mod;
ll res=1;
while(b>0)
{
if(b%2==1)
res=(res*a)%mod;
a=(a*a)%mod;
b/=2;
}
return res;
}
ll dx[]={0, 0, 1, -1};
ll dy[]={1, -1, 0, 0};
ll h, w, cvb;
char a[N][N];
bool used[N][N];
bool inbound(ll x, ll y)
{
return 1<=x && x<=h && 1<=y && y<=w;
}
void dfs(ll x, ll y, char z)
{
used[x][y]=1;
for(ll i=0; i<4; i++)
{
ll nx=x+dx[i];
ll ny=y+dy[i];
if(inbound(nx, ny) && (a[nx][ny]==z || a[nx][ny]=='.') && !used[nx][ny])
{
if(z=='F')
a[nx][ny]='R';
else
a[nx][ny]='F';
dfs(nx, ny, z);
}
}
}
int main()
{
run;
cin>>h>>w;
for(ll i=1; i<=h; i++)
{
for(ll j=1; j<=w; j++)
{
cin>>a[i][j];
}
}
ll cvb=1;
while(true)
{
dfs(h, w, a[h][w]);
set<char>st;
for(ll i=1; i<=h; i++)
{
for(ll j=1; j<=w; j++)
{
st.insert(a[i][j]);
}
}
cvb++;
if(st.size()==2)
break;
}
cout<<cvb<<endl;
}
/*
RRRR
R..R
R..R
RRRR
*/
// By Xanlar
