#include <bits/stdc++.h>
#define int long long
#define debug cout << "ok\n";
#define SQR(x) (1LL * ((x) * (x)))
#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define pii pair<int,int>
#define pli pair<ll,int>
#define vi vector<int>
#define FAST ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef unsigned int ui;
using namespace std;
const int M = 1e9 + 7;
const int INF = 1e9 + 7;
const ll INFLL = (ll)2e18 + 7LL;
const ld PI = acos(-1);
const int dx[] = {1, -1, 0, 0, -1, 1, 1, -1};
const int dy[] = {0, 0, 1, -1, -1, -1, 1, 1};
template<class _, class __>
bool minimize(_ &x, const __ y){
if(x > y){
x = y;
return true;
} else return false;
}
template<class _, class __>
bool maximize(_ &x, const __ y){
if(x < y){
x = y;
return true;
} else return false;
}
template<class _,class __>
void Add(_ &x, const __ y) {
x += y;
if (x >= M) {
x -= M;
}
return;
}
template<class _,class __>
void Diff(_ &x, const __ y) {
x -= y;
if (x < 0) {
x += M;
}
return;
}
//--------------------------------------------------------------
const int MaxN = 5007;
int n,m,res = 0;
char a[MaxN][MaxN];
bool vis[MaxN][MaxN];
bool inSide(int x,int y) {
return 1 <= x && x <= n && 1 <= y && y <= m;
}
void sol() {
cin >> n >> m;
for (int i=1;i<=n;i++) for (int j=1;j<=m;j++) {
cin >> a[i][j];
}
char ch = 'x';
deque<pii> q;
q.push_back(mp(1,1));
vis[1][1] = true;
while (!q.empty()) {
int x = q.front().fi;
int y = q.front().se;
if (a[x][y] != ch) res++;
ch = a[x][y];
q.pop_front();
for (int i=0;i<4;i++) {
int xx = x + dx[i];
int yy = y + dy[i];
if (!inSide(xx,yy) || vis[xx][yy] || a[xx][yy] == '.') continue;
vis[xx][yy] = true;
if (a[xx][yy] == a[x][y]) q.push_front(mp(xx,yy));
else q.push_back(mp(xx,yy));
}
}
cout << res;
}
signed main() {
// freopen("test.inp","r",stdin);
// freopen("test.out","w",stdout);
FAST
int t=1;
// cin >> t;
while (t--) sol();
}
