#include<bits/stdc++.h>
using namespace std;
#define pi pair<int,int>
#define ll long long
#define pb push_back
#define pf push_front
const int MOD = 1e9+7;
const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};
int main()
{
cin.tie(0)->sync_with_stdio(false);
int n, m;
cin >> n >> m;
string s[n];
for(int i=0; i<n; i++)
cin >> s[i];
deque<pi> q;
vector<vector<int>> d(n, vector<int>(m));
vector<vector<bool>> vis(n, vector<bool>(m));
d[0][0] = 0;
q.pb({0, 0});
while(q.size()){
pi u = q.front();
q.pop_front();
if(vis[u.first][u.second]) continue;
vis[u.first][u.second] = true;
for(int i=0; i<4; i++){
int new_x = u.first + dx[i];
int new_y = u.second + dy[i];
if(new_x < 0 or new_x >= n or new_y < 0 or new_y >= m) continue;
if(s[new_x][new_y] == s[u.first][u.second]){
d[new_x][new_y] = d[u.first][u.second];
q.pf({new_x, new_y});
}else if(s[new_x][new_y] != '.'){
d[new_x][new_y] = d[u.first][u.second] + 1;
q.pb({new_x, new_y});
}
}
}
cout << d[n-1][m-1] << '\n';
}
