import sys



def input(): return sys.stdin.readline().strip()

def list2d(a, b, c): return [[c] * b for i in range(a)]

def list3d(a, b, c, d): return [[[d] * c for j in range(b)] for i in range(a)]

def list4d(a, b, c, d, e): return [[[[e] * d for j in range(c)] for j in range(b)] for i in range(a)]

def ceil(x, y=1): return int(-(-x // y))

def INT(): return int(eval(input()))

def MAP(): return list(map(int, input().split()))

def LIST(N=None): return list(MAP()) if N is None else [INT() for i in range(N)]

def Yes(): print('Yes')

def No(): print('No')

def YES(): print('YES')

def NO(): print('NO')

sys.setrecursionlimit(10 ** 9)

INF = 10 ** 19

MOD = 10 ** 9 + 7



def build_grid(H, W, intv, _type, space=True, padding=False):

    # 入力がスペース区切りかどうか

    if space:

        _input = lambda: input().split()

    else:

        _input = lambda: eval(input())

    _list = lambda: list(map(_type, _input()))

    # 余白の有無

    if padding:

        offset = 1

    else:

        offset = 0

    grid = list2d(H+offset*2, W+offset*2, intv)

    for i in range(offset, H+offset):

        row = _list()

        for j in range(offset, W+offset):

            grid[i][j] = row[j-offset]

    return grid



def bfs(grid, src):

    """ BFS(グリッド、重みなし) """

    from collections import deque



    H, W = len(grid), len(grid[0])

    directions = ((1, 0), (-1, 0), (0, 1), (0, -1))

    dist = list2d(H, W, INF)

    que = deque()

    for h, w in src:

        que.append((h, w))

        dist[h][w] = 0

    while que:

        h, w = que.popleft()

        for dh, dw in directions:

            for k in range(1, K+1):

                h2 = h + dh*k

                w2 = w + dw*k

                if grid[h2][w2] == '@':

                    break

                if dist[h2][w2] < dist[h][w] + 1:

                    break

                elif dist[h2][w2] != INF:

                    continue

                dist[h2][w2] = dist[h][w] + 1

                que.append((h2, w2))

    return dist



H, W, K = MAP()

x1, y1, x2, y2 = MAP()

grid = build_grid(H, W, '@', str, space=0, padding=1)



res = bfs(grid, [(x1, y1)])

ans = res[x2][y2]

if ans == INF:

    print((-1))

else:

    print(ans)

import sys



def input(): return sys.stdin.readline().strip()

def list2d(a, b, c): return [[c] * b for i in range(a)]

def list3d(a, b, c, d): return [[[d] * c for j in range(b)] for i in range(a)]

def list4d(a, b, c, d, e): return [[[[e] * d for j in range(c)] for j in range(b)] for i in range(a)]

def ceil(x, y=1): return int(-(-x // y))

def INT(): return int(eval(input()))

def MAP(): return list(map(int, input().split()))

def LIST(N=None): return list(MAP()) if N is None else [INT() for i in range(N)]

def Yes(): print('Yes')

def No(): print('No')

def YES(): print('YES')

def NO(): print('NO')

sys.setrecursionlimit(10 ** 9)

INF = 10 ** 19

MOD = 10 ** 9 + 7



def build_grid(H, W, intv, _type, space=True, padding=False):

    # 入力がスペース区切りかどうか

    if space:

        _input = lambda: input().split()

    else:

        _input = lambda: eval(input())

    _list = lambda: list(map(_type, _input()))

    # 余白の有無

    if padding:

        offset = 1

    else:

        offset = 0

    grid = list2d(H+offset*2, W+offset*2, intv)

    for i in range(offset, H+offset):

        row = _list()

        for j in range(offset, W+offset):

            grid[i][j] = row[j-offset]

    return grid



def bfs(grid, src):

    """ BFS(グリッド、重みなし) """

    from collections import deque



    H, W = len(grid), len(grid[0])

    directions = ((1, 0), (-1, 0), (0, 1), (0, -1))

    dist = list2d(H, W, INF)

    que = deque()

    for h, w in src:

        que.append((h, w))

        dist[h][w] = 0

    while que:

        h, w = que.popleft()

        for dh, dw in directions:

            for k in range(1, K+1):

                h2 = h + dh*k

                w2 = w + dw*k

                if grid[h2][w2] == '@':

                    break

                # 枝刈り

                if dist[h2][w2] < dist[h][w] + 1:

                    break

                elif dist[h2][w2] == dist[h][w] + 1:

                    continue

                else:

                    dist[h2][w2] = dist[h][w] + 1

                    que.append((h2, w2))

    return dist



H, W, K = MAP()

x1, y1, x2, y2 = MAP()

grid = build_grid(H, W, '@', str, space=0, padding=1)



res = bfs(grid, [(x1, y1)])

ans = res[x2][y2]

if ans == INF:

    print((-1))

else:

    print(ans)

import sys


def input():
    return sys.stdin.readline().strip()


def list2d(a, b, c):
    return [[c] * b for i in range(a)]


def list3d(a, b, c, d):
    return [[[d] * c for j in range(b)] for i in range(a)]


def list4d(a, b, c, d, e):
    return [[[[e] * d for j in range(c)] for j in range(b)] for i in range(a)]


def ceil(x, y=1):
    return int(-(-x // y))


def INT():
    return int(eval(input()))


def MAP():
    return list(map(int, input().split()))


def LIST(N=None):
    return list(MAP()) if N is None else [INT() for i in range(N)]


def Yes():
    print("Yes")


def No():
    print("No")


def YES():
    print("YES")


def NO():
    print("NO")


sys.setrecursionlimit(10**9)
INF = 10**19
MOD = 10**9 + 7


def build_grid(H, W, intv, _type, space=True, padding=False):
    # 入力がスペース区切りかどうか
    if space:
        _input = lambda: input().split()
    else:
        _input = lambda: eval(input())
    _list = lambda: list(map(_type, _input()))
    # 余白の有無
    if padding:
        offset = 1
    else:
        offset = 0
    grid = list2d(H + offset * 2, W + offset * 2, intv)
    for i in range(offset, H + offset):
        row = _list()
        for j in range(offset, W + offset):
            grid[i][j] = row[j - offset]
    return grid


def bfs(grid, src):
    """BFS(グリッド、重みなし)"""
    from collections import deque

    H, W = len(grid), len(grid[0])
    directions = ((1, 0), (-1, 0), (0, 1), (0, -1))
    dist = list2d(H, W, INF)
    que = deque()
    for h, w in src:
        que.append((h, w))
        dist[h][w] = 0
    while que:
        h, w = que.popleft()
        for dh, dw in directions:
            for k in range(1, K + 1):
                h2 = h + dh * k
                w2 = w + dw * k
                if grid[h2][w2] == "@":
                    break
                if dist[h2][w2] < dist[h][w] + 1:
                    break
                elif dist[h2][w2] != INF:
                    continue
                dist[h2][w2] = dist[h][w] + 1
                que.append((h2, w2))
    return dist


H, W, K = MAP()
x1, y1, x2, y2 = MAP()
grid = build_grid(H, W, "@", str, space=0, padding=1)
res = bfs(grid, [(x1, y1)])
ans = res[x2][y2]
if ans == INF:
    print((-1))
else:
    print(ans)

import sys


def input():
    return sys.stdin.readline().strip()


def list2d(a, b, c):
    return [[c] * b for i in range(a)]


def list3d(a, b, c, d):
    return [[[d] * c for j in range(b)] for i in range(a)]


def list4d(a, b, c, d, e):
    return [[[[e] * d for j in range(c)] for j in range(b)] for i in range(a)]


def ceil(x, y=1):
    return int(-(-x // y))


def INT():
    return int(eval(input()))


def MAP():
    return list(map(int, input().split()))


def LIST(N=None):
    return list(MAP()) if N is None else [INT() for i in range(N)]


def Yes():
    print("Yes")


def No():
    print("No")


def YES():
    print("YES")


def NO():
    print("NO")


sys.setrecursionlimit(10**9)
INF = 10**19
MOD = 10**9 + 7


def build_grid(H, W, intv, _type, space=True, padding=False):
    # 入力がスペース区切りかどうか
    if space:
        _input = lambda: input().split()
    else:
        _input = lambda: eval(input())
    _list = lambda: list(map(_type, _input()))
    # 余白の有無
    if padding:
        offset = 1
    else:
        offset = 0
    grid = list2d(H + offset * 2, W + offset * 2, intv)
    for i in range(offset, H + offset):
        row = _list()
        for j in range(offset, W + offset):
            grid[i][j] = row[j - offset]
    return grid


def bfs(grid, src):
    """BFS(グリッド、重みなし)"""
    from collections import deque

    H, W = len(grid), len(grid[0])
    directions = ((1, 0), (-1, 0), (0, 1), (0, -1))
    dist = list2d(H, W, INF)
    que = deque()
    for h, w in src:
        que.append((h, w))
        dist[h][w] = 0
    while que:
        h, w = que.popleft()
        for dh, dw in directions:
            for k in range(1, K + 1):
                h2 = h + dh * k
                w2 = w + dw * k
                if grid[h2][w2] == "@":
                    break
                # 枝刈り
                if dist[h2][w2] < dist[h][w] + 1:
                    break
                elif dist[h2][w2] == dist[h][w] + 1:
                    continue
                else:
                    dist[h2][w2] = dist[h][w] + 1
                    que.append((h2, w2))
    return dist


H, W, K = MAP()
x1, y1, x2, y2 = MAP()
grid = build_grid(H, W, "@", str, space=0, padding=1)
res = bfs(grid, [(x1, y1)])
ans = res[x2][y2]
if ans == INF:
    print((-1))
else:
    print(ans)

+                # 枝刈り -                elif dist[h2][w2] != INF: +                elif dist[h2][w2] == dist[h][w] + 1: -                dist[h2][w2] = dist[h][w] + 1 -                que.append((h2, w2)) +                else: +                    dist[h2][w2] = dist[h][w] + 1 +                    que.append((h2, w2))