#include <bits/stdc++.h> #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); } using namespace std; const int N = 4005; const int dx[] = {0, 0, -1, 1}; const int dy[] = {-1, 1, 0, 0}; int r, c; string a[N]; bool vis[N][N]; int ans; void bfs(queue<pair<int, int>> &q1, queue<pair<int, int>> &q2) { if(q1.empty()) return; ++ans; while(!q1.empty()) { int x = q1.front().first, y = q1.front().second; q1.pop(); for(int _ = 0; _ < 4; ++_) { int nx = x + dx[_]; int ny = y + dy[_]; if(nx < 0 || nx >= r || ny < 0 || ny >= c || a[nx][ny] == '.' || vis[nx][ny]) continue; vis[nx][ny] = true; if (a[nx][ny] != a[x][y]) q2.push(make_pair(nx, ny)); else q1.push(make_pair(nx, ny)); } } bfs(q2, q1); } int main() { ios_base::sync_with_stdio(false); cin.tie(0), cout.tie(0); // file("A") else file("task"); cin >> r >> c; for(int i = 0; i < r; ++i) { cin >> a[i]; } queue<pair<int, int>> q1, q2; q1.push(make_pair(0, 0)); vis[0][0] = true; bfs(q1, q2); cout << ans << '\n'; return 0; }