#include <bits/stdc++.h>
#define ii pair<int, int>
#define fi first
#define se second
using namespace std;
const int N = 6e6 + 5;
int n, m, s, rs, cs, re, ce;
int dx[4] = {0, -1, 0, 1};
int dy[4] = {-1, 0, 1, 0};
vector <int> f[N], a[N], p[2][N], ok[N];
queue <ii> q[2];
void upd(int t, int id, int i, int j, int val) {
for(int x = i; x <= j; x++) {
if(t) {
if(!f[id][x]) q[1].push({id, x}), f[id][x] = val;
}
else {
if(!f[x][id]) q[1].push({x, id}), f[x][id] = val;
}
}
}
main () {
cin.tie(0)->sync_with_stdio(0);
if(fopen("task.inp", "r")) {
freopen("task.inp", "r", stdin);
freopen("wa.out", "w", stdout);
}
cin >> m >> n >> s >> rs >> cs >> re >> ce;
for(int i = 1; i <= m; i++) a[i].resize(n + 1), f[i].resize(n + 1), ok[i].resize(n + 1);
for(int i = 1; i <= m; i++) {
for(int j = 0; j <= n + 1; j++) p[1][i].push_back(j);
}
for(int i = 1; i <= n; i++) {
for(int j = 0; j <= m + 1; j++) p[0][i].push_back(j);
}
for(int i = 1; i <= m; i++) {
for(int j = 1; j <= n; j++) {
char ch; cin >> ch;
a[i][j] = (ch == '.' ? 1 : 0);
}
}
q[1].push({rs, cs}); f[rs][cs] = 1;
while (!q[1].empty() || !q[0].empty()) {
while (!q[1].empty()) {
int x, y; tie(x, y) = q[1].front(); q[1].pop();
q[0].push({x, y});
// cout << x << " " << y << " " << f[x][y] << " $$\n";
if(x == re && y == ce) return cout << f[x][y] - 1 << "\n", 0;
for(int i = 0; i < 4; i++) {
int u = x + dx[i], v = y + dy[i];
if(u && u <= m && v && v <= n && !f[u][v] && a[u][v]) {
// cout << x << " " << y << " : " << u << " " << v << "\n";
f[u][v] = f[x][y];
q[1].push({u, v});
// cout << u << " " << v << "*\n";
}
}
}
while (!q[0].empty()) {
int x, y; tie(x, y) = q[0].front(); q[0].pop();
if(s != 1) {
if(x == rs && y == cs) {
int s1 = max(1, x - s), s2 = max(1, y - s);
int s3 = min(m, x + s), s4 = min(n, y + s);
for(int i = s1; i <= s3; i++) {
for(int j = s2; j <= s4; j++) if(!f[i][j]) {
f[i][j] = f[x][y] + 1;
q[1].push({i, j});
}
}
}
else {
int val = f[x][y] + 1;
upd(0, min(n, y + s), max(1, x - s), min(m, x + s), val);
upd(1, min(m, x + s), max(1, y - s), min(n, y + s), val);
upd(0, max(1, y - s), max(1, x - s), min(m, x + s), val);
upd(1, max(1, x - s), max(1, y - s), min(n, y + s), val);
}
}
else {
for(int i = 0; i < 4; i++) {
int u = x + dx[i], v = y + dy[i];
if(u && u <= m && v && v <= n && !f[u][v]) {
f[u][v] = f[x][y] + 1;
q[1].push({u, v});
// cout << u << " " << v << " ****\n";
}
}
}
}
}
}
