#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define ff first
#define ss second
#define all(s) s.begin(),s.end()
#define rall(s) s.rbegin(),s.rend()
ll r,c,n;
ll sr,sc;
ll gr,gc;
vector<vector<ll>>g,dist;
vector<vector<char>>s;
vector<ll>adj,ans;
vector<ll>dx={0,0,-1,1};
vector<ll>dy={-1,1,0,0};
ll G=0;//group number
void dfs(ll x,ll y){
for(ll k=0;k<4;k++){
ll nx=x+dx[k],ny=y+dy[k];
if(nx<1||ny<1||nx>r||ny>c||s[nx][ny]=='#'||g[nx][ny]!=0) continue;
g[nx][ny]=G;
dfs(nx,ny);
}
}
ll calc(ll x,ll y){
if(x>y) swap(x,y);
ll lo=0,hi=r*c;
while(lo<hi){
ll mid=(lo+hi)/2;
ll sum=(n*mid+1)+(mid*n-mid);
if(x+y<=sum&&y<=n*mid+1){
hi=mid;
}
else{
lo=mid+1;
}
}
return lo;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin>>r>>c>>n;
cin>>sr>>sc;
cin>>gr>>gc;
s.resize(r+1);
for(ll i=1;i<=r;i++){
s[i].resize(c+1);
for(ll j=1;j<=c;j++){
cin>>s[i][j];
}
}
g.resize(r+1);
for(ll i=1;i<=r;i++){
g[i].resize(c+1);
}
for(ll i=1;i<=r;i++){
for(ll j=1;j<=c;j++){
if(g[i][j]==0&&s[i][j]=='.'){
G++;
g[i][j]=G;
dfs(i,j);
}
}
}
ans.resize(G+1);
fill(all(ans),1e9);
dist.resize(G+1);
for(ll i=1;i<=G;i++){
dist[i].resize(G+1);
fill(all(dist[i]),1e9);
}
for(ll i=1;i<=r;i++){
for(ll j=1;j<=c;j++){
for(ll x=1;x<=r;x++){
for(ll y=1;y<=c;y++){
if(g[i][j]==0||g[x][y]==0||g[i][j]==g[x][y]) continue;
ll f=calc(abs(i-x),abs(j-y));
ll g1=g[i][j],g2=g[x][y];
dist[g1][g2]=min(dist[g1][g2],f);
dist[g2][g1]=min(dist[g2][g1],f);
}
}
}
}
for(ll i=1;i<=G;i++){
for(ll j=1;j<=G;j++){
if(dist[i][j]==1e9) dist[i][j]=0;
}
}
ans[g[sr][sc]]=0;
set<array<ll,2>>q;
q.insert({0,g[sr][sc]});
while(!q.empty()){
auto [L,x]=*q.begin();
q.erase(q.begin());
if(ans[x]!=L) continue;
for(ll y=1;y<=G;y++){
if(ans[x]+dist[x][y]<ans[y]){
ans[y]=ans[x]+dist[x][y];
q.insert({ans[y],y});
}
}
}
cout<<ans[g[gr][gc]];
}
