#include <bits/stdc++.h>
#define int long long
using namespace std;
const long long N = 4e3 + 5;
int a[N][N];
bool seen[N][N];
int n, m;
bool valid(int i, int j)
{
if (i < 0 or i >= n or j < 0 or j >= m or seen[i][j])
return 0;
return 1;
}
void solve()
{
cin >> n >> m;
char c;
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m; j++)
{
cin >> c;
if (c == 'F')
a[i][j] = 0;
else if (c == '.')
seen[i][j] = 1;
else
a[i][j] = 1;
}
}
queue<pair<int, int>> east, west;
int my, them;
my = a[0][0];
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, -1, 1};
them = 1 ^ my;
east.push({1, 1});
int ans = 0;
do
{
while (east.size())
{
auto t = east.back();
east.pop();
for (int i = 0; i < 4; i++)
{
int fx, fy;
fx = t.first + dx[i], fy = t.second + dy[i];
if (valid(fx, fy))
{
if (my == a[fx][fy])
{
east.push({fx, fy});
seen[fx][fy] = 1;
}
else
{
west.push({fx, fy});
seen[fx][fy] = 1;
}
}
}
}
swap(east, west);
ans++;
} while (east.size());
cout << ans << endl;
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
int t = 1;
// cin >> t;
for (int i = 1; i <= t; i++)
{
// cout << "Case #" << i << ':' << ' ';
solve();
cout << endl;
}
return 0;
}
