Olya loves energy drinks. She loves them so much that her room is full of empty cans from energy drinks.

Formally, her room can be represented as a field of *n* × *m* cells, each cell of which is empty or littered with cans.

Olya drank a lot of energy drink, so now she can run *k* meters per second. Each second she chooses one of the four directions (up, down, left or right) and runs from 1 to *k* meters in this direction. Of course, she can only run through empty cells.

Now Olya needs to get from cell (*x*<sub class="lower-index">1</sub>, *y*<sub class="lower-index">1</sub>) to cell (*x*<sub class="lower-index">2</sub>, *y*<sub class="lower-index">2</sub>). How many seconds will it take her if she moves optimally?

It's guaranteed that cells (*x*<sub class="lower-index">1</sub>, *y*<sub class="lower-index">1</sub>) and (*x*<sub class="lower-index">2</sub>, *y*<sub class="lower-index">2</sub>) are empty. These cells can coincide.
The first line contains three integers *n*, *m* and *k* (1 ≤ *n*, *m*, *k* ≤ 1000) — the sizes of the room and Olya's speed.

Then *n* lines follow containing *m* characters each, the *i*-th of them contains on *j*-th position "#", if the cell (*i*, *j*) is littered with cans, and "." otherwise.

The last line contains four integers *x*<sub class="lower-index">1</sub>, *y*<sub class="lower-index">1</sub>, *x*<sub class="lower-index">2</sub>, *y*<sub class="lower-index">2</sub> (1 ≤ *x*<sub class="lower-index">1</sub>, *x*<sub class="lower-index">2</sub> ≤ *n*, 1 ≤ *y*<sub class="lower-index">1</sub>, *y*<sub class="lower-index">2</sub> ≤ *m*) — the coordinates of the first and the last cells.
In the first sample Olya should run 3 meters to the right in the first second, 2 meters down in the second second and 3 meters to the left in the third second.

In second sample Olya should run to the right for 3 seconds, then down for 2 seconds and then to the left for 3 seconds.

Olya does not recommend drinking energy drinks and generally believes that this is bad.
3 4 4
....
###.
....
1 1 3 1
3
3 4 1
....
###.
....
1 1 3 1
8
2 2 1
.#
#.
1 1 2 2
-1
10 10 1
##########
#.........
#.#######.
#.#.....#.
#.#.###.#.
#.#.#.#.#.
#.#.#.#.#.
#.#.#...#.
#.#.#####.
#.#.......
6 6 10 2
48
10 10 3
##########
##########
##########
##########
##########
##########
##########
#########.
#########.
####..###.
10 6 10 5
1
10 10 3
...##..#..
#.#..#...#
..#.##.#..
##..#..#.#
..#...##..
.#.#.#....
#......#..
.#.####.##
......#...
.#.##...##
4 6 8 1
7
10 10 1000
..........
..........
..........
..........
..........
..........
..........
..........
..........
..........
7 6 1 3
2
10 10 1000
..........
..........
..........
..........
..........
..........
..........
..........
..........
.....#....
3 9 5 1
2
10 10 10
...#......
##.#.#####
...#...###
.#####.###
...#...###
##.#.#####
...#...###
.#####.###
.......###
##########
1 1 1 10
17
2 5 5
#####
##.##
2 3 2 3
0
4 4 4
...#
.#.#
....
##..
1 1 3 4
2
6 6 100
....##
.##.##
.##.##
......
###.##
###.##
1 1 4 6
2
# https://codeforces.com/problemset/problem/877/D
# TLE
import sys
input=sys.stdin.readline

n, m, k =  map(int, input().split())
a       =  ['.'*m for _ in range(n)] 
x1, y1, x2, y2 = map(lambda x: int(x)-1, input().split())

dx    = [0, -1,  0,  1]
dy    = [1,  0, -1,  0]
used  = [[0]*m for _ in range(n)]
D     = [[float('inf')]*m for _ in range(n)]

def direction(dx, dy):
    if dx==0  and dy==1: return 1
    if dx==1  and dy==0: return 2
    if dx==0  and dy==-1:return 4
    if dx==-1 and dy==0: return 8
    
def is_ok(x, y, x_, y_):
    if x+x_ >= 0 and x+x_<n and y+y_>=0 and y+y_<m and a[x+x_][y+y_]=='.' and used[x+x_][y+y_] & direction(x_, y_) == 0:
        return True
    return False

def go(x0, y0, x_, y_, d, S):
    cur=0
    while True:
        if cur==k:
            break
        
        if is_ok(x0, y0, x_, y_): 
            used[x0+x_][y0+y_] |= direction(x_, y_)
            
            D[x0+x_][y0+y_] = min(d, D[x0+x_][y0+y_])
            S.append([x0+x_, y0+y_, D[x0+x_][y0+y_]])
            
            x0  +=  x_
            y0  +=  y_
            cur +=  1
        else:
            break
            
S = [[x1, y1, 0]]
D[x1][y1]    = 0
used[x1][y1] = 15
i = 0

while i < len(S):
    x0, y0, d = S[i]
    for x_, y_ in zip(dx, dy):
        go(x0, y0, x_, y_, d+1, S)
    i+=1

if D[x2][y2] < float('inf'):    
    print(D[x2][y2])
else:
    print(-1)