#define _CRT_SECURE_NO_WARNINGS
#pragma target("avx")
#pragma optimize("O3")
#pragma optimize("unroll-loops")
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <memory>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#define rep(i,n) for(int i=0;i<(lint)(n);i++)
#define REP(i,n) for(int i=1;i<=(lint)(n);i++)
#define all(V) V.begin(),V.end()
typedef long long lint;
typedef unsigned long long ulint;
typedef std::pair<lint, lint> P;
constexpr int INF = INT_MAX/2;
constexpr lint LINF = LLONG_MAX/2;
constexpr double eps = DBL_EPSILON;
constexpr double PI=3.141592653589793238462643383279;
template<class T>
class prique :public std::priority_queue<T, std::vector<T>, std::greater<T>> {};
template <class T, class U>
inline bool chmax(T& lhs, const U& rhs) {
	if (lhs < rhs) {
		lhs = rhs;
		return 1;
	}
	return 0;
}
template <class T, class U>
inline bool chmin(T& lhs, const U& rhs) {
	if (lhs > rhs) {
		lhs = rhs;
		return 1;
	}
	return 0;
}
inline lint gcd(lint a, lint b) {
	while (b) {
		lint c = a;
		a = b; b = c % b;
	}
	return a;
}
inline lint lcm(lint a, lint b) {
	return a / gcd(a, b) * b;
}
bool isprime(lint n) {
	if (n == 1)return false;
	for (int i = 2; i * i <= n; i++) {
		if (n % i == 0)return false;
	}
	return true;
}
template<typename T>
T mypow(T a, unsigned int b) {
	if (!b)return T(1);
	if (b & 1)return mypow(a, b - 1) * a;
	T memo = mypow(a, b >> 1);
	return memo * memo;
}
lint modpow(lint a, lint b, lint m) {
	if (!b)return 1;
	if (b & 1)return modpow(a, b - 1, m) * a % m;
	lint memo = modpow(a, b >> 1, m);
	return memo * memo % m;
}
template<typename T>
void printArray(std::vector<T>& vec) {
	rep(i, vec.size() - 1)std::cout << vec[i] << " ";
	std::cout << vec.back() << std::endl;
}
template<typename T>
void printArray(T l, T r) {
	T rprev = r;
	rprev--;
	for (T i = l; i != rprev; i++) {
		std::cout << *i << " ";
	}
	std::cout << *rprev << std::endl;
}
int h,w,k,sx,sy,gx,gy;
std::vector<std::vector<char>> c;
std::vector<std::vector<lint>> dist;
int f[]={0,1,0,-1};
int g[]={1,0,-1,0};
int main(){
	std::cin>>h>>w>>k;
	c.resize(h,std::vector<char>(w));
	dist.resize(h,std::vector<lint>(w));
	std::cin>>sx>>sy>>gx>>gy;
	sx--;sy--;gx--;gy--;
	rep(i,h){
		rep(j,w){
			std::cin>>c[i][j];
		}
	}
	rep(i,h)rep(j,w)dist[i][j]=LINF;
	dist[sx][sy]=0;
	std::queue<P> que;
	que.push({sx,sy});
	while(!que.empty()){
		P p=que.front();
		que.pop();
		if(p.first==gx&&p.second==gy){
			std::cout<<dist[gx][gy]<<std::endl;
			return 0;
		}
		rep(i,4){
			int ni=p.first,nj=p.second;
			REP(j,k){
				ni+=f[i];nj+=g[i];
				if(ni<0||h<=ni||nj<0||w<=nj)break;
				if(c[ni][nj]=='@')break;
				if(dist[ni][nj]<dist[p.first][p.second]+1)break;
				else if(dist[ni][nj]>dist[p.first][p.second]+1){
					dist[ni][nj]=dist[p.first][p.second]+1;
					que.push({ni,nj});
				}
			}
		}
	}
	std::cout<<-1<<std::endl;
	return 0;
}


Measured memory_bytes: 19904