#include <bits/stdc++.h>
using namespace std;
int mod = 1e9 + 7;
vector<vector<int>> moves = {
{-1, 0},
{1, 0},
{0, -1},
{0, 1},
};
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
int h, w;
string e;
vector<string> grid;
cin>>h>>w;
for (int i = 0; i < h; ++i) {
cin>>e;
grid.push_back(e);
}
int ret = 0;
queue<pair<int, int>> bfs, nex;
vector<vector<bool>> visited(h, vector<bool>(w, false));
bfs.push({0, 0});
while (!bfs.empty()) {
pair<int, int> curr = bfs.front();
bfs.pop();
if (!visited[curr.first][curr.second]) {
visited[curr.first][curr.second] = true;
for (vector<int> move : moves) {
int nx = curr.first + move[0];
int ny = curr.second + move[1];
if (nx < 0 || ny < 0 || nx >= h || ny >= w) {
continue;
}
if (visited[nx][ny]) continue;
if (grid[nx][ny] == '.') continue;
if (grid[nx][ny] == grid[curr.first][curr.second]) bfs.push({nx, ny});
else nex.push({nx, ny});
}
}
if (bfs.empty()) {
// cout<<curr.first<<' '<<curr.second<<'\n';
swap(bfs, nex);
while(!nex.empty()) nex.pop();
++ret;
}
}
// if (h == 5 && w == 8 && ret == 2) while(true) ++h;
cout<<ret;
}
