#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define sz(x) (int)x.size()
#define ALL(v) v.begin(), v.end()
#define MASK(k) (1LL << (k))
#define BIT(x, i) (((x) >> (i)) & 1)
#define INF (ll)1e9
#define oo (ll)1e18
#define MOD (ll)(1e9 + 7)
using namespace std;
template<class T1, class T2>
bool maximize(T1 &a, T2 b){if(a < b){a = b; return true;} return false;}
template<class T1, class T2>
bool minimize(T1 &a, T2 b){if(a > b){a = b; return true;} return false;}
template<class T1, class T2>
void add(T1 &a, T2 b){a += b; if(a >= MOD) a -= MOD;}
template<class T1, class T2>
void sub(T1 &a, T2 b){a -= b; if(a < 0) a += MOD;}
template<class T>
void cps(T &v){sort(ALL(v)); v.resize(unique(ALL(v)) - v.begin());}
void print(vector<pair<int, int>> v){
for(auto x: v) cout << x.first << ' ' << x.second << '\n';
}
int fastPow(int a, int n){
int ans = 1;
while(n){
if(n & 1) ans = 1LL * ans * a % MOD;
a = 1LL * a * a % MOD;
n >>= 1;
}
return ans;
}
ll solve(){
int n, m; cin >> n >> m;
vector<vector<char>> a(n + 3, vector<char>(m + 3));
for(int i = 1; i <= n; i++){
for(int j = 1; j <= m; j++) cin >> a[i][j];
}
vector<vector<int>> mark(n + 3, vector<int>(m + 3, false));
stack<pair<int, int>> Old, New;
Old.push({1, 1});
int ans = 0;
while((int)Old.size()){
ans++;
while((int)Old.size()){
auto [sx, sy] = Old.top();
Old.pop();
if(mark[sx][sy]) continue;
queue<pair<int, int>> q;
q.push({sx, sy});
mark[sx][sy] = true;
while((int)q.size()){
auto [x, y] = q.front();
q.pop();
int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};
for(int k = 0; k < 4; k++){
int nx = x + dx[k], ny = y + dy[k];
if(nx < 1 || ny < 1 || nx > n || ny > m || mark[nx][ny] || a[nx][ny] == '.') continue;
if(a[nx][ny] != a[x][y]){
New.push({nx, ny});
continue;
}
mark[nx][ny] = true;
q.push({nx, ny});
}
}
}
Old = New;
while((int)New.size()) New.pop();
}
cout << ans << '\n';
return 0;
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
int t = 1;
// cin >> t;
while(t--){
solve();
// cout << solve() << '\n';
}
return 0;
}
