from collections import deque

h,w,K = map(int,input().split())

maze = [[x for x in input()] for _ in range(h)]

sx = 0
sy = 0

for i in range(h):
    for j in range(w):
        if maze[i][j] == 'S':
            sx = j
            sy = i

d = [[float('inf')]*w for _ in range(h)]
d[sy][sx] = 0

q = deque([[sy,sx]])
c = 0

while q:
    y,x = q.popleft()
    for j,k in [[1,0],[-1,0],[0,1],[0,-1]]:
        ny,nx = y+j,x+k
        if maze[ny][nx] == '.':
            d[ny][nx] = d[y][x] + 1
            if ny in {0,h-1} or nx in {0,w-1}:
                if d[ny][nx] <= k:
                    print(1)
                    exit()
                else:
                    continue
            else:
                q.append([ny,nx])
                c += 1
    if c >= 4*K**2:
        break
    
visited = [[-1]*w for _ in range(h)]

def BFS(sy,sx):
    q = deque([[sy,sx]])
    visited[sy][sx] = 0
    while q:
        y,x = q.popleft()
        if y == 0 or y == h-1 or x == 0 or x == w-1:
            return visited[y][x]
        for j,k in [[1,0],[-1,0],[0,1],[0,-1]]:
            new_y,new_x = y+j,x+k
            if visited[new_y][new_x] == -1:
                visited[new_y][new_x] = visited[y][x] + 1
                q.append([new_y,new_x])

ans = float('inf')

for i in range(h):
    for j in range(w):
        if d[i][j] <= K:
            ans = min(ans,BFS(i,j))

print((ans-1) // K +2)