#include <bits/stdc++.h>
#define pb push_back
#define ll long long
#define mid (l+r)/2
#define left 2*i+1
#define righ 2*i+2
using namespace std;
int n,m,cnt;
char c[1010][1010];
int dx[]={1,-1,0,0};
int dy[]={0,0,1,-1};
int dfs(int x,int y){
int ret=1;
char cur=c[x][y];
if(c[x][y]=='B')c[x][y]='T';
else c[x][y]='B';
for(int i=0;i<4;i++){
int tox=x+dx[i],toy=y+dy[i];
if(tox<1||tox>n||toy<1||toy>m)continue;
if(cur!=c[tox][toy])continue;
ret+=dfs(tox,toy);
}
return ret;
}
int ans;
int main()
{
cin>>n>>m;
for(int i=1;i<=n;i++){
for(int j=1;j<=m;j++){
cin>>c[i][j];
if(c[i][j]!='*')cnt++;
}
}
while(dfs(1,1)!=cnt)ans++;
cout<<ans+1<<endl;
return 0;
}
