#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define N 400005
#define ff first
#define ss second
#define pb push_back
#define sz(s) (int)s.size()
#define rep(c, a, b) for(c = a; c <= b; c++)
int c[] = {0,0,-1,1};
int d[] = {1,-1,0,0};
ll n, m, cnt = 0, vis[5000][5000];
char a[5000][5000];
queue <pair<int,int>> q, h;
int main () {
ios::sync_with_stdio(0);cin.tie(0);
cin >> n >> m;
for(int i= 1;i<=n;i++) {
for(int j =1;j<=m;j++) {
cin >> a[i][j];
}
}
q.push({1,1});
cnt = 1;
while(!q.empty()) {
int y1 = q.front().ff,y2 = q.front().ss;
bool tr = 0;
q.pop();
for(int i = 0; i < 4; i++) {
int x1 = y1 + c[i], x2 = y2 + d[i];
if(x1 <= 0 || x2 <= 0 || x1 > n || x2 > m || a[x1][x2] == '.') continue;
if(vis[x1][x2]) continue;
vis[x1][x2] = 1;
if(a[x1][x2] != a[y1][y2]) {
h.push({x1,x2});
}
else q.push({x1,x2});
}
a[y1][y2] = '.';
if(q.empty()) {
if(!h.empty())cnt++;
while(!h.empty()) {
q.push({h.front().ff,h.front().ss});
h.pop();
}
cout << '\n';
}
}
cout << cnt << '\n';
}
