#include <bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define X first
#define Y second
const int N=4e3+5;
const int oo=1e9+1;
int n,m;
int d[N][N],dx[]={-1,0,0,1},dy[]={0,-1,1,0};
char s[N][N];
deque <pii> dq;
int bfs01(int u,int v)
{
int x,y,w;
for (int i=1;i<=n;i++)
for (int j=1;j<=m;j++)
d[i][j]=oo;
d[u][v]=1;
dq.push_back(make_pair(u,v));
while (!dq.empty())
{
u=dq.front().X;
v=dq.front().Y;
dq.pop_front();
for (int i=0;i<=3;i++)
{
x=u+dx[i];
y=v+dy[i];
if (x>0 and x<=n and y>0 and y<=m and s[x][y]!='.')
{
w=(s[u][v]!=s[x][y]);
if (d[x][y]>d[u][v]+w)
{
d[x][y]=d[u][v]+w;
if (w==0) dq.push_front(make_pair(x,y));
else dq.push_back(make_pair(x,y));
}
}
}
}
return d[u][v];
}
int main()
{
ios_base::sync_with_stdio(NULL);
cin.tie(NULL); cout.tie(NULL);
cin >> n >> m;
for (int i=1;i<=n;i++)
for (int j=1;j<=m;j++)
cin >> s[i][j];
cout << bfs01(1,1);
}
