#include <bits/stdc++.h>
using namespace std;
#define int long long
#define F first
#define S second
#define INF 10000
int mod = 1e9+7;
typedef pair<int, int> pii;
typedef pair<long, long> pll;
int n,m;
int dx[] = {1,0,-1,0};
int dy[] = {0,1,0,-1};
string s[4040];
bool check(int x, int y){
if(x<0 || x>=n || y<0 || y>=m || s[x][y]=='.'){
return 0;
}
return 1;
}
void solve(){
cin>>n>>m;
for(int i=0;i<n;i++){
cin>>s[i];
}
vector<vector<int>> dis;
vector<vector<int>> vis;
dis = vector<vector<int>>(n+1,vector<int>(m+1,1e18));
vis = vector<vector<int>>(n+1,vector<int>(m+1,0));
dis[0][0] = 1;
deque<pair<int,int>> dq;
dq.push_back({0,0});
while(!dq.empty()){
auto cur = dq.front();
dq.pop_front();
if(vis[cur.F][cur.S]){
continue;
}else{
vis[cur.F][cur.S] = 1;
}
for(int i=0;i<4;i++){
int nx = cur.F+dx[i];
int ny = cur.S+dy[i];
if(check(nx,ny)){
int weight;
if(s[nx][ny]==s[cur.F][cur.S]){
weight = 0;
}else{
weight = 1;
}
if(dis[nx][ny]>dis[cur.F][cur.S]+weight){
dis[nx][ny]=dis[cur.F][cur.S]+weight;
if(weight){
dq.push_back({nx,ny});
}else{
dq.push_front({nx,ny});
}
}
}
}
}
cout<<dis[n-1][m-1]+1<<endl;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int t=1;
//cin>>t;
while(t--){
solve();
}
}
