#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
#define srtl(x)sort(all(x))
#define srtg(x)sort((x).begin(),(x).end(),greater<>())
#define rev(x) reverse(all(x))
#define lb(x,y) lower_bound(x.begin(),x.end(),y)-x.begin()
#define ub(x,y) upper_bound(x.begin(),x.end(),y)-x.begin()
#define ios ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define f first
#define s second
#define pb push_back
#define ins insert
#define next next_permutation
#define _b __builtin_popcount
#define ve vector
#define pii pair<int,int>
#define piii pair<int,pii>
#define vi vector<int>
#define vii vector<pii>
#define viii vector<piii>
#define vvi vector<vi>
//#define vs vector<string>
#define vb vector<bool>
#define pV(x)for(auto i:x)cout<<i<<" ";
#define geta(a){for(auto &i:a)cin>>i;}
#define fr(n)for(int i=0;i<n;i++)
#define Fr(n)for(int i=n-1;i>=0;i--)
#define suma(a)accumulate(a.begin(),a.end(),0LL)
#define br(x){cout<<x<<"\n";return;}
#define yesn cout<<"YES\n";
#define yes()br("YES");
#define no(){br("NO")}
#define alice() br("Alice");
#define bob() br("Bob");
#define cn continue;
#define cint const int
#define int long long
int mod=1000000007;
cint mod1=100000007;
cint mod2=998244353;
int ax[8]={0,1,0,-1,-1,1,1,-1};
int ay[8]={1,0,-1,0,1,-1,1,-1};
//int euc(int a,int b,int c,int d){return abs(a-c)+abs(b-d);}
int bp(int x,int y){
if(y==0)return 1;
int r=bp(x,y/2);
return (y&1)?r*r%mod*x%mod:r*r%mod;
}
int bpm(int x,int y){
if(y==0)return 1;
int r=bp(x,y/2);
return (y&1)?r*r*x:r*r;
}
int cinn(){
int n;
cin>>n;
return n;
}
#define w cinn()
int n,m,k;
bool on(int x,int y){return (x>=0&&x<n&&y>=0&&y<m);}
int xa,xb;
int ya,yb;
vvi ans;
ve<string>v;
void rec(int xx,int yy){
queue<pii>q;
q.push({xx,yy});
while(!q.empty()){
auto [x,y]=q.front();q.pop();
//if(v[x][y]=='.'){
fr(4){
int X=x+ax[i],Y=y+ay[i];
if(on(X,Y)&&ans[X][Y]>ans[x][y]&&v[X][Y]=='.'){
ans[X][Y]=ans[x][y];
q.push({X,Y});
}
}
for(int i=-k;i<=k;i++){
for(int j=-k;j<=k;j++){
int X=x+i,Y=y+j;
if(!on(X,Y))cn;
if(X==xb&&Y==yb){
ans[X][Y]=min(ans[X][Y],ans[x][y]+1);
}
if(abs(i)==abs(j))cn;
if( (abs(i)==k||abs(j)==k) ){
if(ans[X][Y]>ans[x][y]+1){
ans[X][Y]=ans[x][y]+1;
q.push({X,Y});
}
}
}
}
}
}
void solve(){
cin>>n>>m>>k;
cin>>xa>>ya>>xb>>yb;xa--;xb--;ya--;yb--;
ans=vvi(n+1,vi(m+1,9));
v.resize(n);
for(auto&i:v)cin>>i;
ans[xa][ya]=0;
//return;
rec(xa,ya);
cout<<ans[xb][yb];
//cerr<<"\n\n\n";
fr(n){
// for(int j:ans[i])cout<<j<<" ";cout<<"\n";
}
}
int32_t main(){
ios;
int t=1;
//cin>>t;
while(t--){
solve();
}
return 0;
}
/*
2 4 2
1 1
2 4
.###
###.
6 6 1
1 6
6 1
..#.#.
##.###
####.#
...###
##.##.
.#.###
6 7 6
6 4
3 1
..#.#.#
##.##..
.######
#..#.#.
.######
..#.##.
1 15 1
1 15
1 1
...............
*/
