#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <queue>
using namespace std;
#define fast_io ios::sync_with_stdio(0), cin.tie(0)
#define vi vector<int>
#define vvi vector<vi>
#define vs vector<string>
#define pb push_back
int n, m;
vs s;
inline bool in(vi& v) {
return -1 < v[0] && v[0] < n && -1 < v[1] && v[1] < m;
}
inline char f(vi& v) {
return s[v[0]][v[1]];
}
inline int g(vi& v) {
return v[0]*m+v[1];
}
inline bool bad(vi& v) {
return f(v) == '.';
}
inline bool same(vi& v, vi& w) {
return f(v) == f(w);
}
int main() {
fast_io;
vvi adj = {{-1, 0}, {0, -1}, {1, 0}, {0, 1}};
cin >> n >> m;
s = vs(n); for(auto &t: s) cin >> t;
queue<vi> q, nq; vi vis(n*m); int ret = 0;
vi src = {0, 0};
q.push(src), vis[g(src)] = 1;
while(!q.empty()) {
ret++;
while(!q.empty()) {
vi v = q.front(); q.pop(), nq.push(v);
for(auto c: adj) {
vi w = {v[0]+c[0], v[1]+c[1]};
if(!in(w) || vis[g(w)] || bad(w) || !same(v, w)) continue;
q.push(w), vis[g(w)] = 1;
}
}
while(!nq.empty()) {
vi v = nq.front(); nq.pop();
for(auto c: adj) {
vi w = {v[0]+c[0], v[1]+c[1]};
if(!in(w) || vis[g(w)] || bad(w)) continue;
q.push(w), vis[g(w)] = 1;
}
}
}
cout << ret << "\n";
}
