#include <bits/stdc++.h>
#define rep(i, n) for(int i=0; i<(n); ++i)
#define rep2(i, s, n) for(int i=s; i<(n); ++i)
#define ALL(v) (v).begin(), (v).end()

using namespace std;

typedef long long ll;

static const int INTINF = (2147483647 >> 1); // 10^9 + 5000
static const ll LLINF = (9223372036854775807 >> 1);
static const int MAX = 1e5+1;
static const ll MOD = 1e9+7;

namespace Kunitaka{
    template<
        typename TYPE,
        std::size_t SIZE
    >
    std::size_t array_length(const TYPE (&array)[SIZE])
    {
        return SIZE;
    }
}
using namespace Kunitaka;
namespace Printer{
    void br(){
        cout << endl;
    }

    void loop_cnt(int i){
        cout << "i = " << i << endl;
    }

    void loop_cnt(int i, int j){
        cout << "i = " << i << ", " << "j = " << j << endl;
    }

    template<class T>
    void print(T x){
        cout << x << endl;
    }

    template<class T, class S>
    void print(T x, S y){
        cout << x << "," << y << endl;
    }

    template<class T, class S, class U>
    void print(T x, S y, U z){
        cout << x << "," << y << "," << z << endl;
    }

    template<class T, class S>
    void print(pair<T, S> p){
        cout << p.first << ", " << p.second << endl;
    }

    template<
        typename TYPE,
        std::size_t SIZE
    >
    void print(const TYPE (&array)[SIZE]){
        int lim = array_length(array);
        for(int i=0; i<lim; i++){
            if(i) cout << " ";
            cout << array[i];
        }
        cout << endl;
    }

    template<class S>
    void print(vector<S> v){
        for(int i=0; i<v.size(); i++){
            if(i) cout << " ";
            cout<< v[i];
        }
        cout << endl;
    }

    template<class S>
    void print(vector<vector<S> > vv){
        for(int i=0; i<vv.size(); i++){
            for(int j=0; j<vv[i].size(); j++){
                if(j) cout << " ";
                cout << vv[i][j];
            }
            cout << endl;
        }
    }

    void yesno(bool x){
        if(x) cout << "Yes" << endl;
        else cout << "No" << endl;
    }
};
using namespace Printer;

int main(int argc, const char * argv[]) {
    //提出時、消す----//
    //--------------//


    // input
    cout << fixed << setprecision(10);
    int H, W; cin >> H >> W;
    string s[100];
    rep(i, H){
        cin >> s[i];
    }
    bool flip[100][100];
    int dp[100][100];
    rep(i, 100){
        fill(dp[i], dp[i]+100, INTINF);
    }
    memset(flip, false, sizeof(flip));

    rep(i, H){
        rep(j, W){
            if(s[i][j] == '.'){
                if(i == 0 && j == 0) {
                    dp[0][0] = 0;
                    continue;
                }
                int mi = INTINF;
                if(i){
                    mi = min(mi, dp[i-1][j]);
                }
                if(j){
                    mi = min(mi, dp[i][j-1]);
                }
                dp[i][j] = min(dp[i][j], mi);
            }
            else{
                if(i == 0 && j == 0){
                    dp[0][0] = 1;
                    flip[0][0] = true;
                    continue;
                }
                int mi = INTINF;
                if(i){
                    mi = min(mi, dp[i-1][j] + !flip[i-1][j]);
                }
                if(j){
                    mi = min(mi, dp[i][j-1] + !flip[i][j-1]);
                }
                dp[i][j] = min(dp[i][j], mi);
                flip[i][j] = true;
            }
        }
    }

    print(dp[H-1][W-1]);


    
    
    return 0;
}


Measured memory_bytes: 256