/**
* author: wxhtzdy
* created: 12.02.2023 12:30:41
**/
#include <bits/stdc++.h>
using namespace std;
const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};
int n, m;
vector<vector<int>> fenw;
void modify(int i, int j, int v) {
int x = i;
while (x < n) {
int y = j;
while (y < m) {
fenw[x][y] += v;
y |= (y + 1);
}
x |= (x + 1);
}
}
int get(int i, int j) {
int v = 0;
int x = i;
while (x >= 0) {
int y = j;
while (y >= 0) {
v += fenw[x][y];
y = (y & (y + 1)) - 1;
}
x = (x & (x + 1)) - 1;
}
return v;
}
int GetSum(int x1, int y1, int x2, int y2) {
x1 = max(x1, 0);
y1 = max(y1, 0);
x2 = min(x2, n - 1);
y2 = min(y2, m - 1);
return get(x2, y2) - get(x2, y1 - 1) - get(x1 - 1, y2) + get(x1 - 1, y1 - 1);
}
bool Valid(int x, int y) {
return 0 <= x && x < n && 0 <= y && y < m;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int k;
cin >> n >> m >> k;
int sx, sy;
cin >> sx >> sy;
--sx; --sy;
int fx, fy;
cin >> fx >> fy;
--fx; --fy;
vector<string> s(n);
for (int i = 0; i < n; i++) {
cin >> s[i];
}
if (n > m) {
swap(sx, sy);
swap(fx, fy);
vector<string> t(m, string(n, '.'));
for (int j = 0; j < m; j++) {
for (int i = 0; i < n; i++) {
t[j][i] = s[i][j];
}
}
swap(s, t);
swap(n, m);
}
fenw.resize(n);
for (int i = 0; i < n; i++) {
fenw[i].resize(m);
for (int j = 0; j < m; j++) {
fenw[i][j] = 0;
}
}
vector<pair<int, int>> que;
que.emplace_back(sx, sy);
vector<vector<bool>> was(n, vector<bool>(m));
was[sx][sy] = true;
vector<vector<bool>> rem(n, vector<bool>(m));
vector<vector<bool>> qq(n, vector<bool>(m));
vector<pair<int, int>> ff;
vector<pair<int, int>> pp;
vector<vector<pair<int, int>>> cl(n, vector<pair<int, int>>(m, {-1e9, -1e9}));
for (int d = 0; d <= n * m; d++) {
for (int b = 0; b < (int) que.size(); b++) {
int x = que[b].first;
int y = que[b].second;
if (x == fx && y == fy) {
printf("%d\n", d);
return 0;
}
for (int dir = 0; dir < 4; dir++) {
int nx = x + dx[dir];
int ny = y + dy[dir];
if (Valid(nx, ny) && s[nx][ny] == '.' && !was[nx][ny]) {
was[nx][ny] = true;
que.emplace_back(nx, ny);
}
}
}
auto Update = [&](int x, int y, int px, int py) {
int my = max(abs(x - cl[x][y].first), abs(y - cl[x][y].second)) + 1;
int his = max(abs(x - px), abs(y - py)) + 1;
if (his < my) {
cl[x][y] = make_pair(px, py);
}
};
for (auto& p : que) {
int x = p.first;
int y = p.second;
for (int dir = 0; dir < 4; dir++) {
int nx = x + dx[dir];
int ny = y + dy[dir];
if (Valid(nx, ny) && !was[nx][ny] && !rem[nx][ny]) {
rem[nx][ny] = true;
// cout << "updatovo" << " " << nx + 1 << " " << ny + 1 << '\n';
Update(nx, ny, nx, ny);
ff.emplace_back(nx, ny);
}
}
}
for (int b = 0; b < (int) ff.size(); b++) {
int x = ff[b].first;
int y = ff[b].second;
was[x][y] = true;
//cells.emplace_back(p.first, p.second);
for (int dir = 0; dir < 4; dir++) {
int nx = x + dx[dir];
int ny = y + dy[dir];
if (Valid(nx, ny) && !was[nx][ny]) {
Update(nx, ny, cl[x][y].first, cl[x][y].second);
}
if (Valid(nx, ny) && !was[nx][ny] && max(abs(nx - cl[nx][ny].first), abs(ny - cl[nx][ny].second)) + 1 <= k) {
was[nx][ny] = true;
ff.emplace_back(nx, ny);
}
}
}
for (auto& p : pp) {
qq[p.first][p.second] = false;
}
pp.clear();
que = ff;
ff.clear();
}
return 0;
}
