import collections

h,w,k=map(int,input().split())
a=[ [c for c in input()] for _ in range(h)]

s=False
for i in range(h):
    for j in range(w):
        if a[i][j]=="S":
            s=(i,j)
            break
    if s:
        break
min_dis=w*h
dq=collections.deque()
dq.append((0,s[0],s[1]))

moved=[[False for _ in  range(w)] for _ in range(h)]
while dq:
    m,y,x=dq.popleft()
    if moved[y][x]:
        continue
    else:
        moved[y][x]=True
    if m>k:
        continue
    if y==0 or y==h-1 or x==0 or x==w-1:
        print(1)
        exit()
    min_dis=min(min_dis, y, h-1-y, x, w-x-1)
    for dy,dx in ((1,0),(0,1),(-1,0),(0,-1)):
        if 0<=y+dy<h and 0<=x+dx<w and a[y+dy][x+dx] == '.' and not moved[y+dy][x+dx]:
            dq.append((m+1, y+dy, x+dx))
print(1+(min_dis+k-1)//k)