#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template<typename K> using hset = gp_hash_table<K, null_type>;
template<typename K, typename V> using hmap = gp_hash_table<K, V>;
using namespace std;
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define eb emplace_back
#define smax(x, y) (x = max(x, y))
#define smin(x, y) (x = min(x, y))
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define F0R(i, a) FOR(i,0,a)
#define ROF(i, a, b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i, a) ROF(i,0,a)
using ll = long long;
using ld = long double;
template<typename T>
using vv = vector<vector<T>>;
using vi = vector<int>;
using ii = array<int, 2>;
using vii = vector<ii>;
using vvi = vv<int>;
using vll = vector<ll>;
using l2 = array<ll, 2>;
using vl2 = vector<l2>;
using vvll = vv<ll>;
template<typename T>
using minq = priority_queue<T, vector<T>, greater<T>>;
template<typename T>
using maxq = priority_queue<T>;
const ll M = 1000000007;
const ll infll = M * M;
vii dirs{{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
vii adjc(int x, int y) {
vii res;
for (auto [dx, dy] : dirs) {
res.pb({x + dx, y + dy});
}
return res;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int h, w;
cin >> h >> w;
vector<string> g(h);
F0R(r, h) {
cin >> g[r];
}
int res = 0;
int p = '.';
deque<ii> q; // r, c
q.push_front({0, 0});
vvi seen(h, vi(w));
seen[0][0] = 1;
while (!q.empty()) {
assert(q.size() <= h * w);
auto [r, c] = q.front(); q.pop_front();
if (g[r][c] != p) res++;
p = g[r][c];
for (auto [nr, nc] : adjc(r, c)) {
if (0 <= nr && nr < h && 0 <= nc && nc < w && seen[nr][nc] == 0 && g[nr][nc] != '.') {
if (g[nr][nc] == p) q.push_front({nr, nc});
else q.push_back({nr, nc});
seen[nr][nc] = 1;
}
}
}
cout << res << '\n';
}
