# import sys; input = sys.stdin.buffer.readline
# sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

#処理内容
def main():
	H, W = getlist()
	table = []
	for i in range(H):
		l = list(input())
		table.append(l)

	DP = [[INF] * W for i in range(H)]
	DP[0][0] = 0
	for j in range(1, W):
		if table[0][j] == ".":
			DP[0][j] = DP[0][j - 1] + 1
		else:
			DP[0][j] = DP[0][j - 1] + 1 + j

	for i in range(1, H):
		if table[i][0] == ".":
			DP[i][0] = DP[i - 1][0] + 1
		else:
			DP[i][0] = DP[i - 1][0] + 1 + i

	# DP
	for i in range(1, H):
		for j in range(1, W):
			if table[i][j] == ".":
				DP[i][j] = min(DP[i - 1][j], DP[i][j - 1]) + 1
			else:
				DP[i][j] = min(DP[i - 1][j], DP[i][j - 1]) + 1 + i + j


	ans = DP[-1][-1]
	print(ans)

if __name__ == '__main__':
	main()