Buggy python submission (verdict: Time Limit Exceeded):
#!/usr/bin python3
# -*- coding: utf-8 -*-

H, W, K = map(int,input().split())
sth, stw, glh, glw = map(int,input().split())
sth, stw = sth-1, stw-1
glh, glw = glh-1, glw-1

INF = -1
Gmap = [list(input()) for _ in range(H)]
Seen = [[INF]*W for _ in range(H)]
direc = {(1,0), (-1,0), (0,1), (0,-1)}

from collections import deque

def bfs(sth, stw, glh, glw):
    next_q = deque([])
    next_q.append((sth,stw,0))
    Seen[sth][stw] = 0

    while len(next_q)!=0:
        #キュー取り出し(先頭)
        h, w, c = next_q.popleft()
        for dh, dw in direc:
            for sk in range(1,K+1):
                hs, ws = h + dh*sk, w + dw*sk
                if not (0<=hs<H and 0<=ws<W):
                    break
                if Gmap[hs][ws]=='@':
                    break
                if Seen[hs][ws]==INF:
                    next_q.append((hs,ws,c+1))
                    Seen[hs][ws] = c + 1
                if hs==glh and ws==glw:
                    return c + 1
    return -1

def main():
    ret = bfs(sth, stw, glh, glw)
    print(ret)

if __name__ == '__main__':
    main()

Fixed submission:
#!/usr/bin python3
# -*- coding: utf-8 -*-

H, W, K = map(int,input().split())
sth, stw, glh, glw = map(int,input().split())
sth, stw = sth-1, stw-1
glh, glw = glh-1, glw-1

INF = -1
Gmap = [list(input()) for _ in range(H)]
Seen = [[INF]*W for _ in range(H)]
direc = {(1,0), (-1,0), (0,1), (0,-1)}

from collections import deque

def bfs(sth, stw, glh, glw):
    next_q = deque([])
    next_q.append((sth,stw,0))
    Seen[sth][stw] = 0

    while len(next_q)!=0:
        #キュー取り出し(先頭)
        h, w, c = next_q.popleft()
        for dh, dw in direc:
            for sk in range(1,K+1):
                hs, ws = h + dh*sk, w + dw*sk
                if not (0<=hs<H and 0<=ws<W):
                    break
                if Gmap[hs][ws]=='@':
                    break
                if Seen[hs][ws]==INF:
                    next_q.append((hs,ws,c+1))
                    Seen[hs][ws] = c + 1
                elif Seen[hs][ws]<=c:
                    break
                if hs==glh and ws==glw:
                    return c + 1
    return -1

def main():
    ret = bfs(sth, stw, glh, glw)
    print(ret)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
#!/usr/bin python3
# -*- coding: utf-8 -*-

H, W, K = map(int,input().split())
sth,stw,glh, glw = map(int,input().split())
sth, stw = sth-1, stw-1
glh, glw = glh-1, glw-1

INF = -1
Gmap = [list(input()) for _ in range(H)]
Dist = [[INF]*W for _ in range(H)]
direc = {(1,0), (-1,0), (0,1), (0,-1)}
init_q =[]

from collections import deque

def bfs(init,glh,glw):
    next_q = deque([])
    for i in init:
        next_q.append(i)
        Dist[i[0]][i[1]] = 0

    while len(next_q)!=0:
        #キュー取り出し(先頭)
        h,w = next_q.popleft()
        for d in direc:
            for sk in range(1,K+1):
                hs, ws = h + d[0]*sk, w + d[1]*sk
                if not (0<=hs<H and 0<=ws<W):
                    break
                if Gmap[hs][ws]=='@':
                    break
                if Gmap[hs][ws]=='.' and Dist[hs][ws]==INF:
                    next_q.append([hs,ws])
                    Dist[hs][ws] = Dist[h][w] + 1
                if hs==glh and ws==glw:
                    return Dist[hs][ws]
    return -1

def main():
    #固定
    init_q.append([sth, stw])

    ret = bfs(init_q,glh,glw)
    print(ret)


if __name__ == '__main__':
    main()

Fixed submission:
#!/usr/bin python3
# -*- coding: utf-8 -*-

H, W, K = map(int,input().split())
sth, stw, glh, glw = map(int,input().split())
sth, stw = sth-1, stw-1
glh, glw = glh-1, glw-1

INF = -1
Gmap = [list(input()) for _ in range(H)]
Seen = [[INF]*W for _ in range(H)]
direc = {(1,0), (-1,0), (0,1), (0,-1)}

from collections import deque

def bfs(sth, stw, glh, glw):
    next_q = deque([])
    next_q.append((sth,stw,0))
    Seen[sth][stw] = 0

    while len(next_q)!=0:
        #キュー取り出し(先頭)
        h, w, c = next_q.popleft()
        for dh, dw in direc:
            for sk in range(1,K+1):
                hs, ws = h + dh*sk, w + dw*sk
                if not (0<=hs<H and 0<=ws<W):
                    break
                if Gmap[hs][ws]=='@':
                    break
                if Seen[hs][ws]==INF:
                    next_q.append((hs,ws,c+1))
                    Seen[hs][ws] = c + 1
                elif Seen[hs][ws]<=c:
                    break
                if hs==glh and ws==glw:
                    return c + 1
    return -1

def main():
    ret = bfs(sth, stw, glh, glw)
    print(ret)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
#!/usr/bin python3
# -*- coding: utf-8 -*-

H, W, K = map(int,input().split())
sth,stw,glh, glw = map(int,input().split())
sth, stw = sth-1, stw-1
glh, glw = glh-1, glw-1

INF = -1
Gmap = [list(input()) for _ in range(H)]
Dist = [[INF]*W for _ in range(H)]
direc = {(1,0), (-1,0), (0,1), (0,-1)}
init_q =[]

from collections import deque

def bfs(init):
    next_q = deque([])
    for i in init:
        next_q.append(i)
        Dist[i[0]][i[1]] = 0

    while len(next_q)!=0:
        #キュー取り出し(先頭)
        h,w = next_q.popleft()
        for d in direc:
            for sk in range(1,K+1):
                hs, ws = h + d[0]*sk, w + d[1]*sk
                if not (0<=hs<H and 0<=ws<W):
                    break
                if Gmap[hs][ws]=='@':
                    break
                if Gmap[hs][ws]=='.' and Dist[hs][ws]==INF:
                    next_q.append([hs,ws])
                    Dist[hs][ws] = Dist[h][w] + 1
    return Dist

def main():
    #固定
    init_q.append([sth, stw])

    ret = bfs(init_q)
    print(ret[glh][glw])


if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin python3
# -*- coding: utf-8 -*-

H, W, K = map(int,input().split())
sth, stw, glh, glw = map(int,input().split())
sth, stw = sth-1, stw-1
glh, glw = glh-1, glw-1

INF = -1
Gmap = [list(input()) for _ in range(H)]
Seen = [[INF]*W for _ in range(H)]
direc = {(1,0), (-1,0), (0,1), (0,-1)}

from collections import deque

def bfs(sth, stw, glh, glw):
    next_q = deque([])
    next_q.append((sth,stw,0))
    Seen[sth][stw] = 0

    while len(next_q)!=0:
        #キュー取り出し(先頭)
        h, w, c = next_q.popleft()
        for dh, dw in direc:
            for sk in range(1,K+1):
                hs, ws = h + dh*sk, w + dw*sk
                if not (0<=hs<H and 0<=ws<W):
                    break
                if Gmap[hs][ws]=='@':
                    break
                if Seen[hs][ws]==INF:
                    next_q.append((hs,ws,c+1))
                    Seen[hs][ws] = c + 1
                elif Seen[hs][ws]<=c:
                    break
                if hs==glh and ws==glw:
                    return c + 1
    return -1

def main():
    ret = bfs(sth, stw, glh, glw)
    print(ret)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
#!/usr/bin python3
# -*- coding: utf-8 -*-

H, W, K = map(int,input().split())
sth,stw,glh, glw = map(int,input().split())
sth, stw = sth-1, stw-1
glh, glw = glh-1, glw-1

INF = -1
Gmap = [list(input()) for _ in range(H)]
Dist = [[INF]*W for _ in range(H)]
direc = {(1,0), (-1,0), (0,1), (0,-1)}
init_q =[]

from collections import deque

def bfs(init):
    next_q = deque([])
    for i in init:
        next_q.append(i)
        Dist[i[0]][i[1]] = 0

    while len(next_q)!=0:
        #キュー取り出し(先頭)
        h,w = next_q.popleft()
        for d in direc:
            for sk in range(1,K+1):
                hs, ws = h + d[0]*sk, w + d[1]*sk
                if not (0<=hs<H and 0<=ws<W):
                    break
                if Gmap[hs][ws]=='@':
                    break
                if Gmap[hs][ws]=='.' and Dist[hs][ws]==INF:
                    next_q.append([hs,ws])
                    Dist[hs][ws] = Dist[h][w] + 1
    return Dist

def main():
    #固定
    init_q.append([sth, stw])

    ret = bfs(init_q)
    print(ret[glh][glw])


if __name__ == '__main__':
    main()

Fixed submission:
#!/usr/bin python3
# -*- coding: utf-8 -*-

H, W, K = map(int,input().split())
sth, stw, glh, glw = map(int,input().split())
sth, stw = sth-1, stw-1
glh, glw = glh-1, glw-1

INF = -1
Gmap = [list(input()) for _ in range(H)]
Seen = [[INF]*W for _ in range(H)]
direc = {(1,0), (-1,0), (0,1), (0,-1)}

from collections import deque

def bfs(sth, stw, glh, glw):
    next_q = deque([])
    next_q.append((sth,stw,0))
    Seen[sth][stw] = 0

    while len(next_q)!=0:
        #キュー取り出し(先頭)
        h, w, c = next_q.popleft()
        for dh, dw in direc:
            for sk in range(1,K+1):
                hs, ws = h + dh*sk, w + dw*sk
                if not (0<=hs<H and 0<=ws<W):
                    break
                if Gmap[hs][ws]=='@':
                    break
                if Seen[hs][ws]==INF:
                    next_q.append((hs,ws,c+1))
                    Seen[hs][ws] = c + 1
                elif Seen[hs][ws]<=c:
                    break
                if hs==glh and ws==glw:
                    return c + 1
    return -1

def main():
    ret = bfs(sth, stw, glh, glw)
    print(ret)

if __name__ == '__main__':
    main()