#include <bits/stdc++.h>
using namespace std;

template<typename T>
void out(T x) { cout << x << endl; exit(0); }
#define watch(x) cout << (#x) << " is " << (x) << endl





using ll = long long;


const int maxn = 1e6 + 5;
const int inf = 1e9;


int dx[4]={1,-1,0,0};
int dy[4]={0,0,1,-1};

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0);  cout.tie(0);

    int n, m, k;
    cin>>n>>m>>k;

    int x1,y1,x2,y2;
    cin>>x1>>y1>>x2>>y2;
    --x1; --y1; --x2; --y2;

    vector<string> g(n);
    for (int i=0; i<n; i++) {
	cin>>g[i];
    }



    vector<vector<int>> dist(n, vector<int>(m, inf));
    vector<vector<int>> viz(n, vector<int>(m, 0));

    dist[x1][y1] = 0;
    viz[x1][y1] = 0;


    queue<pair<int,int>> qq;
    qq.push({x1,y1});

    while (qq.size()) {
	int x = qq.front().first;
	int y = qq.front().second;
	qq.pop();

	for (int dir=0; dir<4; dir++) {
	    for (int i=1; i<=k; i++) {
		int nx = x+dx[dir]*i;
		int ny = y+dy[dir]*i;
		if (nx<0 || ny<0 || nx>=n || ny>=m) break;
		if (g[nx][ny] == '@') break;
		
		if (1+dist[x][y] > dist[nx][ny]) break;
		if (viz[nx][ny]) continue;

		dist[nx][ny] = 1+dist[x][y];
		viz[nx][ny] = 1;
		qq.push({nx,ny});
	    }
	}
    }

    if (!viz[x2][y2]) out(-1);
    cout<<dist[x2][y2]<<endl;
    
    
    return 0;
}
