#include <bits/stdc++.h>

#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define all(x) (x).begin(), (x).end()
#define ll long long
#define ii pair<int,int>
#define iii pair<ii,ii>
#define vi vector<int>
#define vll vector<ll>
#define vii vector<ii>

using namespace std;

const int INF = 1e9+10;

int dx[] = {0,0,1,-1};
int dy[] = {1,-1,0,0};

int h,w,k,X1,Y1,X2,Y2;
vector<string> g;

int bfs(int x,int y){
	vector<vi> dist(h+10,vi(w+10,-1));
	dist[x][y]=0;
	queue<ii> q;
	q.push({x,y});
	while(!q.empty()){
		ii cur = q.front();
		q.pop();
		for(int i=0;i<4;++i){
			int dxx=cur.ff;
			int dyy=cur.ss;
			for(int j=0;j<k;++j){
				dxx+=dx[i];
				dyy+=dy[i];
				if(dxx<0||dyy<0||dxx>=h||dyy>=w)
					break;
				if(g[dxx][dyy]=='@')
					break;
				if(dist[dxx][dyy]!=-1 && dist[dxx][dyy]<dist[cur.ff][cur.ss]+1)
					break;
				if(dist[dxx][dyy]!=-1 && dist[dxx][dyy]<=dist[cur.ff][cur.ss]+1)
					continue;
				dist[dxx][dyy]=dist[cur.ff][cur.ss]+1;
				q.push(mp(dxx,dyy));
			}
		}
	}
	return dist[X2-1][Y2-1];
}

int32_t main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin>>h>>w>>k>>X1>>Y1>>X2>>Y2;
	g=vector<string>(h);
	for(int i=0;i<h;++i){
		cin>>g[i];
	}
	int ans = bfs(X1-1,Y1-1);
	cout<<ans<<endl;
	return 0;
}