#include <iostream>
#include <vector>
#include <string>
 
using namespace std;
 
class bipart
{
public:
    bipart(int n, int m)
    {
        this->n = n;
        this->m = m;
        edges.resize(n + 1);
    }
    void AddEdge(int x, int y)
    {
        edges[x].push_back(y);
    }
    void GetCuplaj(vector<pair<int, int> > &ret)
    {
        vector<int> to(n+1), from(m+1);
        vector<bool> viz(n+1);
        bool cuplat = true;
        while(cuplat)
        {
            cuplat = false;
            fill(viz.begin(), viz.end(), false);
            for(int i = 1; i <= n; ++i)
                if(to[i] == 0 && cupleaza(i, viz, to, from))
                    cuplat = true;
        }
        for(int i = 1; i <= n; ++i)
            if(to[i] != 0)
                ret.push_back({i, to[i]});
    }
private:
    bool cupleaza(int nod, vector<bool> &viz, vector<int> &to, vector<int> &from)
    {
        if(viz[nod])
            return false;
        viz[nod] = true;
        for(auto v:edges[nod])
            if(from[v] == 0)
            {
               to[nod] = v;
               from[v] = nod;
               return true;
            }
        for(auto v:edges[nod])
            if(cupleaza(from[v], viz, to, from))
            {
                to[nod] = v;
                from[v] = nod;
                return true;
            }
        return false;
    }
    vector<vector<int> > edges;
    int n, m;
};
 
int n, m;
char a[205][205];
 
inline bool isLeftBlack(int i, int j)
{
    if(j == 1 || a[i][j-1] == '.')
        return false;
    return true;
}
 
inline bool isRightBlack(int i, int j)
{
    if(j == m || a[i][j+1] == '.')
        return false;
    return true;
}
 
inline bool isUpBlack(int i, int j)
{
    if(i == 1 || a[i-1][j] == '.')
        return false;
    return true;
}
 
inline bool isDownBlack(int i, int j)
{
    if(i == n || a[i+1][j] == '.')
        return false;
    return true;
}
 
inline int getIndRow(int i, int j)
{
    return (i-1) * m + j;
}
 
inline int getIndCol(int i, int j)
{
    return (i-1) * (m-1) + j;
}
 
int main()
{
    cin >> n >> m;
    bipart graf((n-1) * m, n * (m-1));
    for(int i = 1; i <= n; ++i)
        cin >> (a[i]+1);
    int rasp = 0;
    // rasp = nr_negre - MIS = nr_negre - (noduri - cuplaj) = nr_negre - noduri + cuplaj
    for(int i = 1; i <= n; ++i)
        for(int j = 1; j <= m; ++j)
        {
            if(a[i][j] == '#')
            {
                rasp++; // patratica neagra
                if(isLeftBlack(i, j))
                    rasp--; // pentru fiecare patratel numaram nodul din stanga
                if(isUpBlack(i, j))
                {
                    rasp--; // pentru fiecare patratel numaram nodul de sus
                    if(isLeftBlack(i, j))
                        graf.AddEdge(getIndRow(i-1, j), getIndCol(i, j-1));
                    if(isRightBlack(i, j))
                        graf.AddEdge(getIndRow(i-1, j), getIndCol(i, j));
                }
                if(isDownBlack(i, j))
                {
                    if(isLeftBlack(i, j))
                        graf.AddEdge(getIndRow(i, j), getIndCol(i, j-1));
                    if(isRightBlack(i, j))
                        graf.AddEdge(getIndRow(i, j), getIndCol(i, j));
                }
            }
        }
 
    vector<pair<int, int> > cuplaj;
    graf.GetCuplaj(cuplaj);
 
    cout << rasp + (int)cuplaj.size();
    return 0;
}