#include <bits/stdc++.h>
using namespace std;
#ifdef ngu
#include "debug.h"
#else
#define debug(...) 42
#endif
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
#ifdef ngu
freopen("test.inp", "r", stdin);
freopen("test.out", "w", stdout);
#endif
int r, c, n;
cin >> r >> c >> n;
vector<vector<char>> a(r, vector<char>(c));
vector<vector<int>> d(r, vector<int>(c, -1));
int sr, sc, gr, gc;
cin >> sr >> sc >> gr >> gc;
sr--; sc--; gr--; gc--;
for (int i = 0; i < r; ++i) {
for (int j = 0; j < c; ++j) {
cin >> a[i][j];
}
}
auto inside = [&](int i, int j) {
return 0 <= i && i < r && 0 <= j && j < c;
};
queue<pair<int, int>> W;
queue<tuple<int, int, int, int>> B;
W.emplace(sr, sc);
d[sr][sc] = 0;
while (W.size() || B.size()) {
while (W.size()) {
auto [x, y] = W.front();
W.pop();
for (int dr = 0; dr < 4; ++dr) {
int i = x + dx[dr], j = y + dy[dr];
if (inside(i, j) && d[i][j] == -1) {
if (a[i][j] == '.') {
d[i][j] = d[x][y];
W.emplace(i, j);
} else {
d[i][j] = d[x][y] + 1;
B.emplace(i, j, n - 1, n - 1);
}
}
}
}
while (B.size()) {
auto [x, y, cx, cy] = B.front();
B.pop();
if (cx == 0 || cy == 0) {
W.emplace(x, y);
}
for (int dr = 0; dr < 4; ++dr) {
int i = x + dx[dr], j = y + dy[dr];
int ci = cx - abs(dx[dr]), cj = cy - abs(dy[dr]);
if (inside(i, j) && d[i][j] == -1 && ci >= 0 && cj >= 0) {
d[i][j] = d[x][y];
B.emplace(i, j, ci, cj);
}
}
}
}
cout << d[gr][gc];
}
