#define _CRT_SECURE_NO_WARNINGS

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <limits>
#include <ctime>
#include <cassert>
#include <map>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <stack>
#include <queue>
#include <numeric>
#include <iterator>
#include <bitset>
#include <unordered_map>
#include <unordered_set>

using namespace std;
#define FOR(i,n) for(int i = 0; i < (n); i++)
#define sz(c) ((int)c.size())
#define ten(n) ((int)1e##n)
using ll = long long;
using Pii = pair<int, int>;
using Pll = pair<ll, ll>;

template<typename ...> static inline int getchar_unlocked(void) { return getchar(); }
template<typename ...> static inline void putchar_unlocked(int c) { putchar(c); }
#define mygc(c) (c)=getchar_unlocked()
#define mypc(c) putchar_unlocked(c)
void reader(int& x) { int k, m = 0; x = 0; for (;;) { mygc(k); if (k == '-') { m = 1; break; }if ('0' <= k&&k <= '9') { x = k - '0'; break; } }for (;;) { mygc(k); if (k<'0' || k>'9')break; x = x * 10 + k - '0'; }if (m) x = -x; }
void reader(ll& x) { int k, m = 0; x = 0; for (;;) { mygc(k); if (k == '-') { m = 1; break; }if ('0' <= k&&k <= '9') { x = k - '0'; break; } }for (;;) { mygc(k); if (k<'0' || k>'9')break; x = x * 10 + k - '0'; }if (m) x = -x; }
int reader(char c[]) { int i, s = 0; for (;;) { mygc(i); if (i != ' '&&i != '\n'&&i != '\r'&&i != '\t'&&i != EOF) break; }c[s++] = i; for (;;) { mygc(i); if (i == ' ' || i == '\n' || i == '\r' || i == '\t' || i == EOF) break; c[s++] = i; }c[s] = '\0'; return s; }
int reader(string& c) { int i; for (;;) { mygc(i); if (i != ' '&&i != '\n'&&i != '\r'&&i != '\t'&&i != EOF) break; }c.push_back(i); for (;;) { mygc(i); if (i == ' ' || i == '\n' || i == '\r' || i == '\t' || i == EOF) break; c.push_back(i); }; return sz(c); }
template <class T, class S> void reader(T& x, S& y) { reader(x); reader(y); }
template <class T, class S, class U> void reader(T& x, S& y, U& z) { reader(x); reader(y); reader(z); }
template <class T, class S, class U, class V> void reader(T& x, S& y, U& z, V & w) { reader(x); reader(y); reader(z); reader(w); }
void writer(int x, char c) { int s = 0, m = 0; char f[10]; if (x<0)m = 1, x = -x; while (x)f[s++] = x % 10, x /= 10; if (!s)f[s++] = 0; if (m)mypc('-'); while (s--)mypc(f[s] + '0'); mypc(c); }
void writer(ll x, char c) { int s = 0, m = 0; char f[20]; if (x<0)m = 1, x = -x; while (x)f[s++] = x % 10, x /= 10; if (!s)f[s++] = 0; if (m)mypc('-'); while (s--)mypc(f[s] + '0'); mypc(c); }
void writer(const char c[]) { int i; for (i = 0; c[i] != '\0'; i++)mypc(c[i]); }
void writer(const string& x, char c) { int i; for (i = 0; x[i] != '\0'; i++)mypc(x[i]); mypc(c); }
void writer(const char x[], char c) { int i; for (i = 0; x[i] != '\0'; i++)mypc(x[i]); mypc(c); }
template<class T> void writerLn(T x) { writer(x, '\n'); }
template<class T, class S> void writerLn(T x, S y) { writer(x, ' '); writer(y, '\n'); }
template<class T, class S, class U> void writerLn(T x, S y, U z) { writer(x, ' '); writer(y, ' '); writer(z, '\n'); }
template<class T, class S, class U, class V> void writerLn(T x, S y, U z, V v) { writer(x, ' '); writer(y, ' '); writer(z, ' '); writer(v, '\n'); }
template<class T> void writerArr(T x[], int n) { if (!n) { mypc('\n'); return; }FOR(i, n - 1)writer(x[i], ' '); writer(x[n - 1], '\n'); }
template<class T> void writerArr(vector<T>& x) { writerArr(x.data(), (int)x.size()); }

template<class T> void chmin(T& a, const T& b) { if (a > b) a = b; }
template<class T> void chmax(T& a, const T& b) { if (a < b) a = b; }

template<class T> T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }
template<class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
ll mod_pow(ll a, ll n, ll mod) {
	ll ret = 1;
	ll p = a % mod;
	while (n) {
		if (n & 1) ret = ret * p % mod;
		p = p * p % mod;
		n >>= 1;
	}
	return ret;
}
template<class T> T extgcd(T a, T b, T& x, T& y) { for (T u = y = 1, v = x = 0; a;) { T q = b / a; swap(x -= q * u, u); swap(y -= q * v, v); swap(b -= q * a, a); } return b; }
ll mod_inv(ll a, ll m) { ll x, y; extgcd<ll>(a, m, x, y); return (m + x % m) % m; }

#ifdef _MSC_VER
template <typename ... Args>
void debugPrintf(const char *format, Args const & ... args) {
	fprintf(stderr, format, args ...);
	fflush(stderr);
}
#else
#define debugPrintf(...)
#endif

const int MAX_N = 100000;
int match[MAX_N];
bool used[MAX_N];

bool dfs(vector<vector<int>>& G, int v) {
	used[v] = true;
	for (auto u : G[v]) {
		int w = match[u];
		if (w < 0 || !used[w] && dfs(G, w)) {
			match[v] = u;
			match[u] = v;
			return true;
		}
	}
	return false;
}

int bipartite_matching(vector<vector<int>>& G) {
	int ret = 0;
	memset(match, -1, sizeof(match));
	FOR(v, sz(G)) {
		if (match[v] < 0) {
			memset(used, 0, sizeof(used));
			if (dfs(G, v)) ret++;
		}
	}
	return ret;
}

int main() {
	int n, m;
	while (cin >> n >> m && n) {
		static char b[100][101];
		FOR(i, n) cin >> b[i];
		vector<vector<int>> f(n - 1);
		FOR(i, n - 1) FOR(j, m - 1) {
			int cur = 0;
			FOR(x, 2) FOR(y, 2) {
				int tmp = b[i + x][j + y] == '#';
				cur += tmp *(1 << (2 * x + y));
			}
			f[i].push_back(cur);
		}

		int specialCount = 0;
		FOR(i, n - 1) FOR(j, m - 1) {
			int t = f[i][j];
			bool ok = false;
			FOR(k, 4) if (t == 15 - (1 << k)) ok = true;
			if (!ok) continue;
			specialCount++;
		}

		vector<pair<Pii, Pii>> g[2];
		auto add_edge = [&](Pii a, Pii b) {
			if (a.first == b.first) g[0].emplace_back(a, b);
			else g[1].emplace_back(a, b);
		};

		FOR(i, n - 1) {
			Pii tmp = { -1,-1 };
			FOR(j, m - 1) {
				int cur = f[i][j];
				if (cur == 15 - 1 || cur == 15 - 4) {
					tmp = Pii(i, j);
				} else if(cur == 15 - 2 || cur == 15 - 8) {
					if(tmp.first != -1) {
						add_edge(tmp, Pii(i, j));
						tmp.first = -1;
					}
				} else if (cur == 15) {
					continue;
				} else {
					tmp.first = -1;
				}
			}
		}
		FOR(j, m - 1) {
			Pii tmp = { -1,-1 };
			FOR(i, n - 1) {
				int cur = f[i][j];
				if (cur == 15 - 1 || cur == 15 - 2) {
					tmp = Pii(i, j);
				} else if (cur == 15 - 4 || cur == 15 - 8) {
					if (tmp.first != -1) {
						add_edge(tmp, Pii(i, j));
						tmp.first = -1;
					}
				} else if (cur == 15) {
					continue;
				} else {
					tmp.first = -1;
				}
			}
		}

		vector<vector<int>> g2(sz(g[0]) + sz(g[1]));
		FOR(i, sz(g[0])) {
			FOR(j, sz(g[1])) {
				auto a = g[0][i].first, b = g[0][i].second;
				auto c = g[1][j].first, d = g[1][j].second;

				bool intersected1 = a.second <= c.second && c.second <= b.second;
				bool intersected2 = c.first <= a.first && a.first <= d.first;
				if (intersected1 && intersected2) {
					int u = i, v = sz(g[0]) + j;
					g2[u].push_back(v);
					g2[v].push_back(u);
				}
			}
		}

		int matched = bipartite_matching(g2);
		int unmatched = sz(g2) - matched;
		int ans = specialCount - unmatched + 1;
		cout << ans << endl;
	}
	return 0;
}


Measured memory_bytes: 3872