#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int mxH=505, mxW=505;
int H, W;
char grid[mxH][mxW], rChange[4]={0, 1, 0, -1}, cChange[4]={1, 0, -1, 0};
bool vis[mxH][mxW];
vector<pair<int, int>> dir;
void floodfill(int r, int c, char curr) {
stack<pair<int, int>> frontier;
frontier.push({r, c});
while(!frontier.empty()) {
r=frontier.top().first;
c=frontier.top().second;
frontier.pop();
if(r<0||r>=H||c<0||c>=W||vis[r][c]) {
continue;
}
if(grid[r][c]!=curr&&grid[r][c]!='.') {
dir.push_back({r, c});
continue;
}
for(int i=0; i<4; ++i) {
if(vis[r+rChange[i]][c+cChange[i]])
continue;
vis[r+rChange[i]][c+cChange[i]]=1;
frontier.push({r+rChange[i], c+cChange[i]});
}
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> H >> W;
for(int i=0; i<H; ++i) {
for(int j=0; j<W; ++j) {
cin >> grid[i][j];
}
}
vis[0][0]=1;
int ans=0;
dir.push_back({0, 0});
while(1) {
if(dir.empty())
break;
for(pair<int, int> p : dir) {
floodfill(p.first, p.second, grid[p.first][p.second]);
dir.erase(remove(dir.begin(), dir.end(), p), dir.end());
}
++ans;
}
cout << ans+1;
}
