/*
 * zyrch - Rupanshu Yadav
 */
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <fstream>
#include <queue>
#include <deque>
#include <bitset>
#include <iterator>
#include <list>
#include <stack>
#include <map>
#include <set>
#include <functional>
#include <utility>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iomanip>
#include <cassert>
#include <sstream>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef double db;
typedef string str;

typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;

typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<ld> vd;
typedef vector<str> vs;
typedef vector<pi> vpi;
typedef vector<pl> vpl;

#define fast_cin() ios_base::sync_with_stdio(false); cin.tie(NULL) 

#define forn(i,a,b) for (int i = (a); i < ll(b); ++i)
#define fo(i,a) forn(i,0,ll(a))
#define rforn(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define ro(i,a) rforn(i,0,a)
#define trav(a,x) for (auto& a: x)

#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define rsz resize
#define ins insert

#define mp make_pair
#define pb push_back
#define eb emplace_back
#define f first
#define s second

void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

const ll INF = 1e18;

ll mod = 1000000007;
inline ll fast_expo(ll base,ll power,ll modulo=mod){
    base%=modulo;
    if (base<0) base+=modulo;
    ll x=base,cnt=power,ans=1;
    while(cnt){
        if (cnt&1) ans=(ans*x)%modulo;
        x=(x*x)%modulo;
        cnt>>=1;
    }
    return ans;
}

ll takemod(ll a, ll mo){
	a %= mo;
	if(a < 0) a+=mo;
	return a;
}

// if mod is prime
ll modinv(ll a, ll mo){
	return takemod(fast_expo(takemod(a,mo), mo-2, mo), mo);
}

//=========================CODE STARTS HERE=============================//
ll h, w;
vector<vector<char>> matrix;

ll dp[105][105][2];

int solve(int ii, int jj, char prev) {
	
	if (dp[ii][jj][prev == '#'] != -1) 
		return dp[ii][jj][prev == '#'];
	
	int count = 0;
	int ans;
	if (ii == h - 1 && jj == w  - 1) {
		ans = (matrix[ii][jj] == '#' && prev == '.');
	}else if (ii == h - 1) {
		if (matrix[ii][jj] == '#' && prev == '.') {
			count = 1;
		}
		ans = count + solve(ii, jj + 1, matrix[ii][jj]);
	}else if (jj == w - 1) {
		if (matrix[ii][jj] == '#' && prev == '.') {
			count = 1;
		}
		ans = count + solve(ii + 1, jj, matrix[ii][jj]);
	}else {
		if (matrix[ii][jj] == '#' && prev == '.') {
			count = 1;
		}
		ans = count + min(solve(ii + 1, jj, matrix[ii][jj]), solve(ii, jj + 1, matrix[ii][jj]));
	}
	dp[ii][jj][prev == '#'] = ans;
	return ans;
}
	
int main() {
	
	fo(i, 105) {
		fo(j, 105) {
			dp[i][j][0] = -1;
			dp[i][j][1] = -1;
		}
	}
	
	cin >> h >> w;
 	matrix.resize(h);
 	fo(i, h) {
		matrix[i].resize(w);
	}
 	fo(i, h) {
		fo(j, w) {
			cin >> matrix[i][j];
		}
	}
	
	
	cout << solve(0, 0, matrix[0][0]) + (matrix[0][0] == '#') << endl;
 	//~ fo(i, h) {
		//~ fo(j, h) {
			//~ cout << dp[i][j][0] << " ";
		//~ }
		//~ cout << endl;
	//~ }
	return 0; 
}


Measured memory_bytes: 384