// header {{{
// header {{{
#include <bits/stdc++.h>
using namespace std;
 
#define CPP_STR(x) CPP_STR_I(x)
#define CPP_CAT(x,y) CPP_CAT_I(x,y)
#define CPP_STR_I(args...) #args
#define CPP_CAT_I(x,y) x ## y
 
#define ASSERT(expr...) assert((expr))
 
using i8  = int8_t;
using u8  = uint8_t;
using i16 = int16_t;
using u16 = uint16_t;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
 
using f32 = float;
using f64 = double;
// }}}
 
constexpr i64 INF = 1'010'000'000'000'000'017LL;
 
constexpr i64 MOD = 1'000'000'007LL;
 
constexpr f64 EPS = 1e-12;
 
constexpr f64 PI = 3.14159265358979323846;

#define M5 100007
#define M9 1000000000

 
// util {{{
#define FOR(i, start, end) for(i64 i = (start), CPP_CAT(i,xxxx_end)=(end); i < CPP_CAT(i,xxxx_end); ++i)
#define REP(i, n) FOR(i, 0, n)
 
#define ALL(f,c,...) (([&](decltype((c)) cccc) { return (f)(std::begin(cccc), std::end(cccc), ## __VA_ARGS__); })(c))
#define ll long long int
#define VI vector <int>
template<typename C>
i64 SIZE(const C& c) { return static_cast<i64>(c.size()); }
 
template<typename T, size_t N>
i64 SIZE(const T (&)[N]) { return static_cast<i64>(N); }
 
template<typename T, typename U, typename Comp=less<>>
bool chmax(T& xmax, const U& x, Comp comp={}) {
    if(comp(xmax, x)) {
        xmax = x;
        return true;
    }
    return false;
}
 
template<typename T, typename U, typename Comp=less<>>
bool chmin(T& xmin, const U& x, Comp comp={}) {
    if(comp(x, xmin)) {
        xmin = x;
        return true;
    }
    return false;
}
// }}}
 
// init {{{
struct ProconInit {
    static constexpr int IOS_PREC = 15;
    static constexpr bool AUTOFLUSH = false;
 
    ProconInit() {
        cin.tie(nullptr);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(IOS_PREC);
        if(AUTOFLUSH)
            cout << unitbuf;
    }
} PROCON_INIT;
// }}}
 
//--------------------------------------------------------------------
 
bool isOK(int mid, double key){
 
    if((double)mid*mid > key) {
             return true;
     } else {
              return false;
     }
}

 int binary_search(double key) {
    int left = -1; //「index = 0」が条件を満たすこともあるので、初期値は -1
    int right = 2000000000;
    /* どんな二分探索でもここの書き方を変えずにできる！ */
    while (right - left > 1) {
        int mid = left + (right - left) / 2;

        if (isOK(mid, key)) right = mid;
        else left = mid;
    }

    /* left は条件を満たさない最大の値、right は条件を満たす最小の値になっている */
    return right;
}
int N; 

int p(char a1, char a2){
    if(a1 == '.'){
        return 0;
    } else{
        if(a2 == '#'){
            return 0;
        } else{
            return 1;
        }
    }
}

void solve() {
    int H,W;
    string a[100];
    cin >> H >> W;
    REP(i,H){
        string w;
        cin >> w;
        a[i] = w;
    }

    int dp[102][102];
    dp[0][0] = p(a[0][0], 'x'); 
    FOR(i,1,H){
        dp[i][0] = dp[i-1][0] + p(a[i][0],a[i-1][0]);
    }
    FOR(i,1,W){
        dp[0][i] = dp[0][i-1] + p(a[0][i],a[0][i-1]);
    }
    FOR(i,1,H){
        FOR(j,1,W){
            if(a[i][j] == '.'){
                dp[i][j] = min(dp[i-1][j],dp[i][j-1]);
            } else{
                dp[i][j] = min(dp[i-1][j]+p(a[i][j],a[i-1][j]),dp[i][j-1]+p(a[i][j],a[i][j-1]));
            }
        }
    }
/*    REP(i,H){
        REP(j,W){
            cout << dp[i][j];      
        }
        cout << endl;
    }
*/
cout << dp[H-1][W-1];
}
 
signed main() {
 
    solve();
 
    return 0;
}


Measured memory_bytes: 384