#include<bits/stdc++.h>

using namespace std;
 
/// ----------------------------- (Debug) ------------------------------
#define sim template < class c
#define ris return * this
#define dor > debug & operator <<
#define eni(x) sim > typename enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; }; sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0); sim > char dud(...);
struct debug {
#ifndef ONLINE_JUDGE
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i));}
sim, class b dor(pair < b, c > d) {ris << "(" << d.first << ", " << d.second << ")";}
sim dor(rge<c> d) {*this << "["; for (auto it = d.b; it != d.e; ++it) *this << ", " + 2 * (it == d.b) << *it; ris << "]";}
#else
sim dor(const c&) { ris; }
#endif
};
vector<char*> tokenizer(const char* args) {
	char *token = new char[111]; strcpy(token, args); token = strtok(token, ", ");
	vector<char*> v({token});
	while(token = strtok(NULL,", ")) v.push_back(token);
	return reverse(v.begin(), v.end()), v;
}
void debugg(vector<char*> args) { cerr << "\b\b "; }
template <typename Head, typename... Tail>
void debugg(vector<char*> args, Head H, Tail... T) {
	debug() << " [" << args.back() << ": " << H << "] ";
	args.pop_back(); debugg(args, T...);
}
#define harg(...) #__VA_ARGS__
#ifndef ONLINE_JUDGE
#define dbg(...) { debugg(tokenizer(harg(__VA_ARGS__, \b\t-->Line)), __VA_ARGS__, __LINE__); cerr << endl;}
#else
#define dbg(...) { }
#endif
/// -----------------------------------------------------------------------
 
typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pi;
typedef vector<pi> vpi; 
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)    
#define F first
#define S second
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define print(x) cout << x << "\n";
#define REP(i,a,b) for(i=a;i<=b;i++)
#define RAP(i,a,b) for(i=a;i>=b;i--)
#define spa <<" "<<
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)x.size()
ll mod=998244353;
const int MX=0x3f3f3f3f;
const int N = 1e5 + 5;
 
int n, m, k;
int x11, y11, x2, y2;
int dx[4]={-1, +1, 0, 0};
int dy[4]={0, 0, +1, -1};
vector<vector<char> > a;
vector<vector<int> > vis, ways, dist;
 
void bfs(int x, int y)
{
	queue<pair<int, int> > q;
	q.push({x, y});
	vis[x][y] = 1;
	dist[x][y] = 0;
	while(!q.empty())
	{
		int x=q.front().first;
		int y=q.front().second;
		q.pop();
		for(int dir=0;dir<4;dir++)
		{
			for(int len = 1; len <= k; len++)
			{
				int nx=x+dx[dir] * len;
				int ny=y+dy[dir] * len;
				if(nx<1 || ny<1 || nx>n || ny>m)
					break;
				if(vis[nx][ny] && dist[x][y] + 1 > dist[nx][ny])
					break;
				if(a[nx][ny] == '@')
					break;
				if(vis[nx][ny]){
					//dbg(dist[nx][ny],dist[x][y]+1);
					continue;
				}
				dist[nx][ny]=dist[x][y]+1;
				vis[nx][ny]=1;
				q.push({nx, ny});
			}
		}
	}
}
 
int main()
{
	IOS;
	cin >> n >> m >> k;
	cin >> x11 >> y11 >> x2 >> y2;
	a = vector<vector<char> > (n + 1, vector<char> (m + 1));
	vis = ways = dist = vector<vector<int> > (n + 1, vector<int> (m + 1, 0));
	for(int i = 1; i <= n; i++)
		for(int j = 1; j <= m; j++)
			cin >> a[i][j];
	bfs(x11, y11);
	if(!vis[x2][y2])
		cout << -1;
	else
		cout << dist[x2][y2];
	return 0;
}




Measured memory_bytes: 32456