#include <algorithm>
#include <iostream>
#include <cstring>
#include <set>
using namespace std;
const int N = 6000000;
const int ddi[] = { -1, 0, 1, 0 };
const int ddj[] = { 0, 1, 0, -1 };
char tt[N + 1], *aa[N];
set<int> jj[N], ii[N];
int *dd[N], qu[N * 2], head, cnt;
int n, m;
void update(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;
jj[i].erase(j);
ii[j].erase(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);
for (int i = 0; i < n; i++)
for (int j = 0; j < m; j++) {
jj[i].insert(j);
ii[j].insert(i);
}
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;
update(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);
update(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) {
auto it = jj[i_].lower_bound(jl);
if (it == jj[i_].end())
break;
j_ = *it;
if (j_ > jr)
break;
update(i_, j_, 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) {
auto it = ii[j_].lower_bound(il);
if (it == ii[j_].end())
break;
i_ = *it;
if (i_ > ir)
break;
update(i_, j_, d + 1, 1);
}
}
}
}
cout << ans << '\n';
return 0;
}
