#pragma GCC optimize("O3")
#include <bits/stdc++.h>
struct DSU{
int n;
std::vector<int> p;
std::vector<int> sz;
std::vector<int> right;
DSU(int n):n(n){
p.resize(n);
sz.resize(n);
right.resize(n);
for(int i =0 ;i < n;i++){
p[i] = i;
sz[i] = 1;
right[i] = i;
}
}
DSU() = default;
int pred(int a){
if(p[a] == a)return a;
p[a] = pred(p[a]);
return p[a];
}
void mer(int a,int b){
a = pred(a),b = pred(b);
if(a == b)return;
if(sz[a] > sz[b]){
std::swap(a,b);
}
p[a] = b;
sz[b] += sz[a];
right[b] = std::max(right[b],right[a]);
}
};
void del(int x,int y,std::vector<DSU>& hor,
std::vector<std::vector<bool>>& ban_hor,
std::vector<std::vector<bool>>& ban_vert,
std::vector<DSU>& vert,int r,int c){
// std::cout<<"dsjf"<<std::endl;
if(x + 1 < r && ban_vert[x + 1][y]){
vert[y].mer(x,x + 1);
}
if(x - 1 >= 0 && ban_vert[x - 1][y]){
vert[y].mer(x - 1,x);
}
if(y + 1 < c && ban_hor[x][y + 1]){
hor[x].mer(y,y + 1);
}
if(y - 1 >= 0 && ban_vert[x][y - 1]){
hor[x].mer(y - 1,y);
}
ban_hor[x][y] = true;
ban_vert[x][y] = true;
// std::cout<<"dsjf"<<std::endl;
}
struct Event{
bool type;
int ind;
int l,r;
Event(bool type,int ind,int l,int r):type(type),ind(ind),l(l),r(r){};
Event() = default;
};
signed
main()
{
std::ios::sync_with_stdio(false);
std::cin.tie(0);
int r,c,n;
std::cin>>r>>c>>n;
std::pair<int,int> start;
std::cin>>start.first>>start.second;
start.first--;
start.second--;
std::pair<int,int> stop;
std::cin>>stop.first>>stop.second;
stop.first--;
stop.second--;
std::vector<std::vector<char>> a(r,std::vector<char>(c));
for(int i=0 ;i < r;i++){
for(int j =0 ;j < c;j++){
std::cin>>a[i][j];
}
}
std::vector<std::vector<int>> dist(r,std::vector<int>(c,1e8));
std::vector<DSU> hor(r);
std::vector<std::vector<bool>> ban_hor(r,std::vector<bool>(c,false));
for(int i =0 ;i < r;i++){
hor[i] = DSU(c);
}
std::vector<DSU> vert(c);
std::vector<std::vector<bool>> ban_vert(r,std::vector<bool>(c,false));
for(int i =0 ;i <c;i++){
vert[i] = DSU(r);
}
// std::cout<<"dhjf"<<std::endl;
std::deque<std::pair<int,int>> help;
help.push_front(start);
dist[start.first][start.second] = 0;
del(start.first,start.second,hor,ban_hor,ban_vert,vert,r,c);
while(help.size() > 0){
auto v = help.front();
// std::cout<<v.first<<' '<<v.second<<' '<<dist[v.first][v.second]<<std::endl;
help.pop_front();
std::vector<int> dx = {0,0,-1,1};
std::vector<int> dy = {1,-1,0,0};
for(int i =0 ;i < dx.size();i++){
if(v.first + dx[i] >= 0 && v.first + dx[i] < r &&
v.second + dy[i] >=0 && v.second + dy[i] < c &&
dist[v.first + dx[i]][v.second + dy[i]] > dist[v.first][v.second] &&
a[v.first + dx[i]][v.second + dy[i]] == '.'){
dist[v.first + dx[i]][v.second + dy[i]] = dist[v.first][v.second];
del(v.first + dx[i],v.second + dy[i],hor,ban_hor,ban_vert,vert,r,c);
help.push_front({v.first + dx[i],v.second + dy[i]});
}
}
// std::cout<<"djhfs;jlfj"<<std::endl;
int abs_x = std::abs(v.first - stop.first);
int abs_y = std::abs(v.second - stop.second);
if(abs_x <= n && abs_y <= n && abs_x + abs_y != 2 * n){
if(dist[stop.first][stop.second] > dist[v.first][v.second] + 1){
// std::cout<<dist[v.first][v.second] + 1<<std::endl;
dist[stop.first][stop.second] = dist[v.first][v.second] + 1;
del(stop.first,
stop.second,hor,ban_hor,ban_vert,vert,r,c);
}
}
dx = {v.first - n + 1,v.first + n - 1,v.first - n + 1,v.first + n - 1};
dy = {v.second - n + 1,v.second - n + 1,v.second + n - 1,v.second + n - 1};
for(int i = 0 ;i < dx.size();i++){
if(dx[i] >= 0 && dx[i] < r && dy[i] >=0 && dy[i] < c){
if(dist[dx[i]][dy[i]] > dist[v.first][v.second] + 1){
dist[dx[i]][dy[i]] = dist[v.first][v.second] + 1;
del(dx[i],dy[i],hor,ban_hor,ban_vert,vert,r,c);
help.push_back({dx[i],dy[i]});
}
}
}
std::vector<Event> all;
if(v.second + n < c){
all.push_back(Event(0,v.second + n,std::max(0,v.first - n + 1),
std::min(r - 1,v.first + n - 1)));
}
if(v.second - n >= 0){
all.push_back(Event(0,v.second - n,
std::max(0,v.first - n + 1),std::min(r - 1,v.first + n - 1)));
}
if(v.first + n < r){
all.push_back(Event(1,v.first + n,std::max(0,v.second - n + 1),std::min(c - 1,v.second + n - 1)));
}
if(v.first - n >= 0){
all.push_back(Event(1,v.first - n,std::max(0,v.second - n + 1),std::min(c - 1,v.second + n - 1)));
}
for(auto now:all){
// std::cout<<"aaa"<<std::endl;
// std::cout<<now.ind<<' '<<now.type<<' '<<now.l<<' '<<now.r<<std::endl;
if(now.type == 0){
do{
// std::cout<<"aaa"<<std::endl;
int tmp = -1;
if(!ban_vert[now.l][now.ind]){
tmp = now.l;
}else{
tmp = vert[now.ind].right[vert[now.ind].pred(now.l)];
tmp++;
}
// std::cout<<tmp<<std::endl;
// std::cout<<tmp.left<<' '<<tmp.max<<' '<<vert[now.ind].query(0,0,r,tmp.left,tmp.left + 1).max<<std::endl;
if(tmp > now.r)break;
if(dist[tmp][now.ind] > dist[v.first][v.second] + 1){
dist[tmp][now.ind] = dist[v.first][v.second] + 1;
help.push_back({tmp,now.ind});
}
del(tmp,now.ind,hor,ban_hor,ban_vert,vert,r,c);
// std::cout<<tmp.left<<' '<<tmp.max<<' '<<vert[now.ind].query(0,0,r,now.l,now.r + 1).max<<std::endl;
// exit(0);
}while(true);
}else{
do{
// std::cout<<now.l<<' '<<now.r<<' '<<now.type<<' '<<' '<<now.ind<<std::endl;
int tmp = -1;
if(!ban_hor[now.ind][now.l]){
tmp = now.l;
}else{
tmp = hor[now.ind].right[hor[now.ind].pred(now.l)];
// std::cout<<tmp<<std::endl;
tmp++;
}
// std::cout<<tmp<<' '<<hor[now.ind].right[hor[now.ind].pred(now.l)]<<' '<<!ban_hor[now.ind][now.l]<<std::endl;
if(tmp > now.r)break;
if(dist[now.ind][tmp] > dist[v.first][v.second] + 1){
dist[now.ind][tmp] = dist[v.first][v.second] + 1;
help.push_back({now.ind,tmp});
}
del(now.ind,tmp,hor,ban_hor,ban_vert,vert,r,c);
}while(true);
}
}
// std::cout<<"djf"<<std::endl;
}
// for(int i=0;i < r;i++){
// for(int j =0 ;j < c;j++){
// std::cout<<dist[i][j]<<' ';
// }
// std::cout<<std::endl;
// }
std::cout<<dist[stop.first][stop.second];
}
