#include <bits/stdc++.h>
#define L(i,j,k) for(int i=(j);i<=(k);i++)
#define R(i,j,k) for(int i=(j);i>=(k);i--)
#define all(x) x.begin(),x.end()
#define sz(a) ((int)a.size())
#define pb push_back
using namespace std;
typedef long long ll;
const int N=3000,INF=1e9;
const int di[]={1,-1,0,0};
const int dj[]={0,0,1,-1};
vector<string>A;
int r,c,n;
void chmin(int &a,int b){
a=min(a,b);
}
bool safe(int x,int y){
return x>=0&&x<r&&y>=0&&y<c;
};
int anc[N][N];
queue<pair<int,int>>q,q1,q2;
vector<vector<int>>dist;
vector<vector<bool>>disp;
void bfs_reachable(){
vector<pair<int,int>>add;
while(sz(q)){
auto [i,j]=q.front();q.pop();
L(k,0,3){
int ni=i+di[k],nj=j+dj[k];
if(safe(ni,nj)&&disp[ni][nj]){
disp[ni][nj]=false;
if(A[ni][nj]!='#'){
q.push({ni,nj});
}else{
add.pb({ni,nj});
q1.push({ni,nj});
}
}
}
}
for(auto x:add){
q.push(x);
}
}
void bfs_extend(){
while(sz(q1)){
auto [i,j]=q1.front();q1.pop();
L(k,1,n-1){
int ni=i+k;
if(safe(ni,j)&&disp[ni][j]){
A[ni][j]='.';
disp[ni][j]=false;
q2.push({ni,j});
}
ni=i-k;
if(safe(ni,j)&&disp[ni][j]){
A[ni][j]='.';
disp[ni][j]=false;
q2.push({ni,j});
}
}
}
while(sz(q2)){
auto [i,j]=q2.front();q2.pop();
L(k,1,n-1){
int nj=j+k;
if(safe(i,nj)&&disp[i][nj]){
A[i][nj]='.';
disp[i][nj]=false;
q.push({i,nj});
}
nj=j-k;
if(safe(i,nj)&&disp[i][nj]){
A[i][nj]='.';
disp[i][nj]=false;
q.push({i,nj});
}
}
}
}
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin>>r>>c>>n;
int sr,sc,gr,gc;cin>>sr>>sc>>gr>>gc;
sr--,sc--,gr--,gc--;
A.resize(r);
dist.resize(r,vector<int>(c,INF));
disp.resize(r,vector<bool>(c,INF));
L(i,0,r-1){
cin>>A[i];
}
int ans=0;
disp[sr][sc]=false;
q.push({sr,sc});
bfs_reachable();
while(1){
if(!disp[gr][gc])break;
ans++;
bfs_extend();
bfs_reachable();
}
cout<<ans<<endl;
}
