from collections import deque
H,W,K=map(int,input().split())
A=[list(input())for _ in range(H)]
for i,a in enumerate(A):
	if"S"in a:y,x=(i,a.index("S"))
d=1e9
Q=deque([(0,y,x)])
while Q:
	c,i,j=Q.popleft()
	d=min(d,i,j,H-i-1,W-j-1)
	if c>=K:continue
	for ni,nj in((i+1,j),(i,j+1),(i-1,j),(i,j-1)):
		if 0<=ni<H and 0<=nj<W and A[ni][nj]==".":
			A[ni][nj]=""
			Q+=[(c+1,ni,nj)]
print(1-(-d//K))