#include <bits/stdc++.h>
using namespace std;

int dx[4] = {0, 0, 1, -1};
int dy[4] = {1, -1, 0, 0};

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int h, w, k; cin >> h >> w >> k;
    int x1, y1, x2, y2; cin >> x1 >> y1 >> x2 >> y2;
    x1--, y1--, x2--, y2--;
    string S[h];
    for (int i = 0; i < h; i++) cin >> S[i];
    constexpr int inf = 1e9;
    vector<vector<int>> D(h, vector<int>(w, inf));
    D[x1][y1] = 0;
    queue<tuple<int, int>> Q; Q.emplace(x1, y1);
    auto in = [&](int x, int y) {
        return 0 <= x && x < h && 0 <= y && y < w && S[x][y] != '@';
    };
    while (!Q.empty()) {
        auto [x, y] = Q.front(); Q.pop();
        int d = D[x][y] + 1;
        for (int i = 0; i < 4; i++) {
            int s = x, t = y;
            for (int j = 0; j < k; j++) {
                s += dx[i], t += dy[i];
                if (!in(s, t)) break;
                if (D[s][t] < d) break;
                if (D[s][t] > d) {
                    D[s][t] = d;
                    Q.emplace(s, t);
                }
            }
        }
    }
    if (D[x2][y2] == inf) D[x2][y2] = -1;
    cout << D[x2][y2] << "\n";
    return 0;
}