package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

type Tuple struct {
	x int
	y int
}

func main() {
	sc := NewScanner()

	H, W, K := sc.NextInt(), sc.NextInt(), sc.NextInt()
	matrix := make([][]bool, H)

	checked := make([][]bool, H)

	l := make([][]int, H)
	sx := 0
	sy := 0

	for i := 0; i < H; i++ {
		matrix[i] = make([]bool, W)
		checked[i] = make([]bool, W)

		l[i] = make([]int, W)

		p := sc.NextLine()
		for j := 0; j < W; j++ {
			matrix[i][j] = p[j] != '#'
			if p[j] == 'S' {
				sy = i
				sx = j
			}
		}
	}

	for i := 0; i < H; i++ {
		for j := 0; j < W; j++ {
			l[i][j] = mins(i/K, j/K, (W-i)/K, (H-j)/K) + 1
		}
	}

	queue := make([]Tuple, 1)
	queue[0] = Tuple{x: sx, y: sy}
	mn := l[sy][sx] + 1
	for i := 0; i < len(queue); i++ {
		for x := -1; x <= 1; x++ {
			for y := -1; y <= 1; y++ {
				if abs(x)+abs(y) != 1 {
					continue
				}
				nx := queue[i].x + x
				ny := queue[i].y + y
				if -1 == nx || nx == W {
					fmt.Println(1)
					return
				}
				if -1 == ny || ny == H {
					fmt.Println(1)
					return
				}

				if abs(nx-sx)+abs(ny-sy) > K {
					continue
				}

				if checked[ny][nx] {
					continue
				}
				checked[ny][nx] = true
				if !matrix[ny][nx] {
					continue
				}

				if mn == -1 || mn > l[ny][nx] {
					mn = l[ny][nx] + 1
				}
				queue = append(queue, Tuple{x: nx, y: ny})

			}
		}

	}
	fmt.Println(mn)
}
func abs(a int) int {
	if a < 0 {
		return -a
	}
	return a
}

func mins(a ...int) int {
	m := a[0]
	for i := 1; i < len(a); i++ {
		if m > a[i] {
			m = a[i]
		}
	}
	return m
}

func min(a int, b int) int {
	if a < b {
		return a
	}
	return b
}

type Scanner struct {
	r   *bufio.Reader
	buf []byte
	p   int
}

func NewScanner() *Scanner {
	rdr := bufio.NewReaderSize(os.Stdin, 1000)
	return &Scanner{r: rdr}
}
func (s *Scanner) Next() string {
	s.pre()
	start := s.p
	for ; s.p < len(s.buf); s.p++ {
		if s.buf[s.p] == ' ' {
			break
		}
	}
	result := string(s.buf[start:s.p])
	s.p++
	return result
}
func (s *Scanner) NextLine() string {
	s.pre()
	start := s.p
	s.p = len(s.buf)
	return string(s.buf[start:])
}
func (s *Scanner) NextInt() int {
	v, _ := strconv.Atoi(s.Next())
	return v
}
func (s *Scanner) NextInt64() int64 {
	v, _ := strconv.ParseInt(s.Next(), 10, 64)
	return v
}

func (s *Scanner) NextIntArray() []int {
	s.pre()
	start := s.p
	result := []int{}
	for ; s.p < len(s.buf)+1; s.p++ {
		if s.p == len(s.buf) || s.buf[s.p] == ' ' {
			v, _ := strconv.ParseInt(string(s.buf[start:s.p]), 10, 0)
			result = append(result, int(v))
			start = s.p + 1
		}
	}

	return result
}
func (s *Scanner) NextInt64Array() []int64 {
	s.pre()
	start := s.p
	result := []int64{}
	for ; s.p < len(s.buf)+1; s.p++ {
		if s.p == len(s.buf) || s.buf[s.p] == ' ' {
			v, _ := strconv.ParseInt(string(s.buf[start:s.p]), 10, 64)
			result = append(result, v)
			start = s.p + 1
		}
	}
	return result
}

func (s *Scanner) NextMap() map[int]bool {
	s.pre()
	start := s.p
	mp := map[int]bool{}
	for ; s.p < len(s.buf); s.p++ {
		if s.buf[s.p] == ' ' {
			v, _ := strconv.Atoi(string(s.buf[start:s.p]))
			mp[v] = true
			start = s.p + 1
		}
	}
	v, _ := strconv.Atoi(string(s.buf[start:s.p]))
	mp[v] = true

	return mp
}

func (s *Scanner) pre() {
	if s.p >= len(s.buf) {
		s.readLine()
		s.p = 0
	}
}
func (s *Scanner) readLine() {
	s.buf = make([]byte, 0)
	for {
		l, p, e := s.r.ReadLine()
		if e != nil {
			panic(e)
		}
		s.buf = append(s.buf, l...)
		if !p {
			break
		}
	}
}
