#include<bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
const int dir[4][2]={{0,1},{1,0},{0,-1},{-1,0}};
int N,R,C,sr,sc,gr,gc;
vector<vector<char> >W;string s;
vector<vector<bool> >V;
vector<int>a,b,na,nb;
vector<int>c,d,e,f;
void sol0(int x,int y,int N){
	for(int j=1,p=y-1;j<=N&&p>=1;j++,p--){
		if(V[x][p])break;V[x][p]=1;
		na.push_back(x),nb.push_back(p);
	}
	for(int j=1,p=y+1;j<=N&&p<=C;j++,p++){
		if(V[x][p])break;V[x][p]=1;
		na.push_back(x),nb.push_back(p);
	}
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0),cout.tie(0);
	cin>>R>>C>>N;W.resize(R+1);
	for(int i=1;i<=R;i++)W[i].resize(C+1);
	cin>>sr>>sc>>gr>>gc;
	for(int i=1;i<=R;i++){
		string s;cin>>s;
		for(int j=1;j<=C;j++)W[i][j]=s[j-1];
	}
	V.resize(R+1);for(int i=1;i<=R;i++)V[i].resize(C+1);
	a.push_back(sr),b.push_back(sc);
	for(int ans=0;;ans++){
		queue<int>qu,qv;
		for(int i=0;i<a.size();i++){
			if(a[i]==gr&&b[i]==gc)return cout<<ans,0;
			qu.push(a[i]),qv.push(b[i]);
		}
		while(!qu.empty()){
			int x=qu.front(),y=qv.front();qu.pop(),qv.pop();
			if(x==gr&&y==gc)return cout<<ans,0;
			for(int d=0;d<4;d++){
				int xx=x+dir[d][0],yy=y+dir[d][1];
				if(xx>0&&yy>0&&xx<=R&&yy<=C&&!V[xx][yy]&&W[xx][yy]=='.')
					V[xx][yy]=1,qu.push(xx),qv.push(yy),a.push_back(xx),b.push_back(yy);
			}
		}
		na.clear(),nb.clear();
		c.clear(),d.clear(),e.clear(),f.clear();
		for(int i=0;i<a.size();i++){
			c.push_back(a[i]),d.push_back(b[i]);
			for(int j=1,p=a[i]-1;j<N&&p>=1;j++,p--){
				if(V[p][b[i]])break;V[p][b[i]]=1;
				c.push_back(p),d.push_back(b[i]);
				na.push_back(p),nb.push_back(b[i]);
			}
			for(int j=1,p=a[i]+1;j<N&&p<=R;j++,p++){
				if(V[p][b[i]])break;V[p][b[i]]=1;
				c.push_back(p),d.push_back(b[i]);
				na.push_back(p),nb.push_back(b[i]);
			}
		}
		for(int i=0;i<a.size();i++){
			if(a[i]-N>=1&&!V[a[i]-N][b[i]]){
				V[a[i]-N][b[i]]=1;
				e.push_back(a[i]-N),f.push_back(b[i]);
				na.push_back(a[i]-N),nb.push_back(b[i]);
			}
			if(a[i]+N<=R&&!V[a[i]+N][b[i]]){
				V[a[i]+N][b[i]]=1;
				e.push_back(a[i]+N),f.push_back(b[i]);
				na.push_back(a[i]+N),nb.push_back(b[i]);
			}
		}
		for(int i=0;i<c.size();i++)sol0(c[i],d[i],N);
		for(int i=0;i<e.size();i++)sol0(e[i],f[i],N-1);
		swap(a,na),swap(b,nb);
	}
}