import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


enum INF = 10^^9;

void main() {
  try {
    for (; ; ) {
      const H = readInt();
      const W = readInt();
      auto S = new string[H];
      foreach (x; 0 .. H) {
        S[x] = readToken();
      }
      
      auto dp = new int[][](H, W);
      foreach (x; 0 .. H) foreach (y; 0 .. W) {
        dp[x][y] = INF;
      }
      dp[0][0] = (S[0][0] == '#') ? 1 : 0;
      
      auto vis = new bool[][](H, W);
      foreach (x; 0 .. H) foreach (y; 0 .. W) {
        if (x + 1 < H && S[x + 1][y] != '#') chmin(dp[x + 1][y], dp[x][y]);
        if (y + 1 < W && S[x][y + 1] != '#') chmin(dp[x][y + 1], dp[x][y]);
        foreach (xx; x .. H) foreach (yy; y .. W) {
          vis[xx][yy] = (x == xx && y == yy) ||
                        (S[xx][yy] == '#' && x < xx && vis[xx - 1][yy]) ||
                        (S[xx][yy] == '#' && y < yy && vis[xx][yy - 1]);
          if (vis[xx][yy]) {
            chmin(dp[xx][yy], dp[x][y] + 1);
            if (x == 0 && y == 0) {
              chmin(dp[xx][yy], 1);
            }
          }
        }
      }
      debug {
        foreach (x; 0 .. H) {
          writeln(dp[x]);
        }
      }
      writeln(dp[H - 1][W - 1]);
    }
  } catch (EOFException e) {
  }
}
