#include <bits/stdc++.h>
using namespace std ;
typedef long long ll ;
typedef long double ld ;
typedef pair<int, int> pii ;
typedef pair<int, long long> pil ;
typedef pair<long long, int> pli ;
typedef pair<long long, long long> pll ;
#define bitc(n) (__builtin_popcountll(n))
#define clz(n) (__builtin_clzll(n))
#define ctz(n) (__builtin_ctzll(n))
#define lgi(n) (31 - __builtin_clz(n))
#define lgl(n) (63 - __builtin_clzll(n))
#define MASK(k) (1ll << (k))
#define getbit(n, k) ((n) >> (k) & 1)
#define flipbit(n, k) ((n) ^ (1ll << (k)))
#define ton(n, k) ((n) | (1ll << (k)))
#define toff(n, k) ((n) & ~(1ll << (k)))
#define fi first
#define se second
#define mp make_pair
#define eb emplace_back
#define lwb lower_bound
#define upb upper_bound
#define sz(x) (int)(x.size())
#define all(x) x.begin(),x.end()
#define taskname "maze"
template<class X, class Y>
bool maximize(X &x, const Y &y) {
if(x < y) {
return x = y, true ;
}
return false ;
}
template<class X, class Y>
bool minimize(X &x, const Y &y) {
if(x > y) {
return x = y, true ;
}
return false ;
}
template<class X>
void removeDup(vector<X> &ve) {
sort(ve.begin(), ve.end()) ;
ve.resize(unique(ve.begin(), ve.end()) - ve.begin()) ;
}
const ll INF = 1e18 ;
const int inf = 1e9 ;
const int mod = 1e9 + 7 ;
const int N = 3e3 + 5, M = 6e6 + 5, LG = 17 ;
const int X[] = {-1, 1, 0, 0} ;
const int Y[] = {0, 0, 1, -1} ;
/* Some Peach Tea Is Great ;-; */
/* Author : Tuandq */
vector<bool> a[N] ;
int r, c, n ;
pii st, en ;
bool inside(const int &i, const int &j) {
return 0 < i && i <= r && 0 < j && j <= c ;
}
int dis[M] ;
bitset<M> vis ;
int encode(const int &i, const int &j) {
return (i - 1) * c + j - 1 ;
}
pii decode(const int &x) {
return mp(x / c + 1, x % c + 1) ;
}
namespace sub1 {
bool checkSub() {
return n == 1 ;
}
void solve() {
memset(dis, 0x0f, sizeof dis) ;
deque<int> q ;
dis[encode(st.fi, st.se)] = 0 ;
q.emplace_back(encode(st.fi, st.se)) ;
while(!q.empty()) {
int u = q.front() ; q.pop_front() ;
if(vis[u]) continue ;
vis.set(u) ;
pii cur = decode(u) ;
for(int d = 0; d < 4; d ++) {
int x = cur.fi + X[d] ;
int y = cur.se + Y[d] ;
if(!inside(x, y)) continue ;
int w = !a[x][y] ;
int nxt = encode(x, y) ;
if(minimize(dis[nxt], dis[u] + w)) {
if(!w) q.emplace_front(nxt) ;
else q.emplace_back(nxt) ;
}
}
}
cout << dis[encode(en.fi, en.se)] ;
}
}
namespace sub2 {
bool checkSub() {
return r * c <= 1e3 ;
}
void solve() {
memset(dis, 0x0f, sizeof dis) ;
deque<int> q ;
dis[encode(st.fi, st.se)] = 0 ;
q.emplace_back(encode(st.fi, st.se)) ;
while(!q.empty()) {
int u = q.front() ; q.pop_front() ;
if(vis[u]) continue ;
vis.set(u) ;
pii cur = decode(u) ;
for(int d = 0; d < 4; d ++) {
int x = cur.fi + X[d] ;
int y = cur.se + Y[d], nxt = encode(x, y) ;
if(inside(x, y) && a[x][y] && minimize(dis[nxt], dis[u])) {
q.emplace_front(nxt) ;
}
}
for(int x = cur.fi - n; x <= cur.fi + n; x ++) {
for(int y = cur.se - n; y <= cur.se + n; y ++) {
if(inside(x, y) && mp(x, y) != cur) {
if(abs(cur.fi - x) + abs(cur.se - y) == (n << 1)) continue ;
int nxt = encode(x, y) ;
if(minimize(dis[nxt], dis[u] + 1)) {
q.emplace_back(nxt) ;
}
}
}
}
}
// for(int i = 1; i <= r; i ++) {
// for(int j = 1; j <= c; j ++) cerr << dis[encode(i, j)] << ' ' ;
// cerr << endl ;
// }
cout << dis[encode(en.fi, en.se)] ;
}
}
void kittncool() {
cin >> r >> c >> n >> st.fi >> st.se >> en.fi >> en.se ;
for(int i = 1; i <= r; i ++) {
a[i].assign(c + 2, false) ;
for(int j = 1; j <= c; j ++) {
char t ; cin >> t ;
if(t == '.') a[i][j] = true ;
}
}
// for(int i = 1; i <= r; i ++) {
// for(int j = 1; j <= c; j ++) cerr << a[i][j] << ' ' ;
// cerr << endl ;
// }
// return ;
if(sub1::checkSub()) return sub1::solve() ;
if(sub2::checkSub()) return sub2::solve() ;
}
signed main() {
ios_base::sync_with_stdio(0) ; cin.tie(0) ; cout.tie(0) ;
if(fopen(taskname".inp", "r")) {
freopen(taskname".inp", "r", stdin) ;
// freopen(taskname".out", "w", stdout) ;
}
int t = 1 ; //cin >> t ;
while(t --) {
kittncool() ;
}
}
