#include <algorithm>
#include <iostream>
#include <cstring>
#include <set>
using namespace std;
const int N = 6000000;
const int N_ = 1 << 23;
const int ddi[] = { -1, 0, 1, 0 };
const int ddj[] = { 0, 1, 0, -1 };
char tt[N + 1], *aa[N];
bool st[2][N_ << 1]; int n_;
int *dd[N], qu[N * 2], head, cnt;
int n, m;
void pul(int z, int i) {
int l = i << 1, r = l ^ 1;
st[z][i] = st[z][l] || st[z][r];
}
void pull(int z, int i) {
while (i >>= 1)
pul(z, i);
}
void build() {
for (n_ = 1; n_ < n * m; n_ <<= 1)
;
for (int z = 0; z < 2; z++) {
for (int i = 0; i < n * m; i++)
st[z][i + n_] = true;
for (int i = n_ - 1; i; i--)
pul(z, i);
}
}
void update(int z, int i) {
st[z][i += n_] = false, pull(z, i);
}
int search(int z, int l) {
int r = n_ - 1;
for (l += n_, r += n_; l <= r; l >>= 1, r >>= 1)
if (l & 1) {
if (st[z][l]) {
while (l < n_)
if (!st[z][l <<= 1])
l ^= 1;
return l - n_;
}
l++;
}
return n_;
}
void assign(int i, int j, int d, int w) {
if (dd[i][j] <= d)
return;
dd[i][j] = d;
if (!w)
qu[--head] = i * m + j, cnt++;
else
qu[head + cnt++] = i * m + j;
update(0, i * m + j);
update(1, j * n + i);
}
int main() {
ios_base::sync_with_stdio(false), cin.tie(NULL);
int k; cin >> n >> m >> k;
int is, js; cin >> is >> js, is--, js--;
int it, jt; cin >> it >> jt, it--, jt--;
for (int i = 0; i < n; i++)
cin >> tt, aa[i] = strdup(tt);
build();
for (int i = 0; i < n; i++) {
dd[i] = new int[m];
for (int j = 0; j < m; j++)
dd[i][j] = n * m;
}
head = n * m;
assign(is, js, 0, 0);
int ans = n * m;
while (cnt--) {
int ij = qu[head++], i = ij / m, j = ij % m, d = dd[i][j];
if (i - k <= it && it <= i + k && j - k <= jt && jt <= j + k && abs(it - i) + abs(jt - j) != k * 2)
ans = min(ans, d + 1);
for (int h = 0; h < 4; h++) {
int i_ = i + ddi[h], j_ = j + ddj[h];
if (0 <= i_ && i_ < n && 0 <= j_ && j_ < m && aa[i_][j_] == '.') {
if (i_ == it && j_ == jt)
ans = min(ans, d);
assign(i_, j_, d, 0);
}
if (h % 2 == 0) {
int jl = max(j - k + 1, 0), jr = min(j + k - 1, m - 1);
i_ = i + ddi[h] * k;
if (0 <= i_ && i_ < n)
while (true) {
int ij = search(0, i_ * m + jl);
if (ij > i_ * m + jr)
break;
assign(i_, ij - i_ * m, d + 1, 1);
}
} else {
int il = max(i - k + 1, 0), ir = min(i + k - 1, n - 1);
j_ = j + ddj[h] * k;
if (0 <= j_ && j_ < m)
while (true) {
int ji = search(1, j_ * n + il);
if (ji > j_ * n + ir)
break;
assign(ji - j_ * n, j_, d + 1, 1);
}
}
}
}
cout << ans << '\n';
return 0;
}
