#include <bits/stdc++.h>
using namespace std;
#define FOR(i,j,k) for(int i = j; i <= k; ++i)
#define pb push_back
#define pf push_front
#define pp pair<int, int>
#define F first
#define S second
#define p2 pair<pp, pp>
const int N = 2500;
int n, m, k, sx, sy, ex, ey;
vector<string> a(N);
vector<pp> dist[N];
bool inb(int x, int y){
return (x >= 1 && x <= n && y >= 1 && y <= m);
}
pp per(int x, int y){
return pp({x, y});
}
bool eq(pp x, pp y){
return (x.F == y.F && x.S == y.S);
}
bool grt(pp x, pp y){
return (x.F > y.F || (x.F == y.F && x.S > y.S));
}
int dx[8] = {0, 0, -1, 1, -1, -1, 1, 1};
int dy[8] = {-1, 1, 0, 0, -1, 1, -1, 1};
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
cin >> sx >> sy >> ex >> ey;
FOR(i,1,min(n,m))
FOR(j,1,max(n,m)+1)
a[i].pb('.'), dist[i].pb({-1, -1});
if (n > m){
FOR(i,1,n) FOR(j,1,m) cin >> a[j][i];
swap(n, m); swap(sx, sy); swap(ex, ey);
}
else{
FOR(i,1,n) FOR(j,1,m) cin >> a[i][j];
}
/*FOR(i,1,n){
FOR(j,1,m) cout << a[i][j];
cout << '\n';
}*/
deque<p2> q;
dist[sx][sy] = {0, 0};
q.pb({{sx, sy}, {0, 0}});
while (!q.empty()){
p2 t = q.front(); q.pop_front();
int x = t.F.F, y = t.F.S, d1 = t.S.F, d2 = t.S.S;
if (!eq(dist[x][y], per(d1, d2))) continue;
if (d2 < 0){
FOR(i,0,7){
int nx = x + dx[i], ny = y + dy[i];
if (inb(nx, ny) && (eq(dist[nx][ny], per(-1, -1)) || grt(dist[nx][ny], per(d1, d2 + 1)))){
dist[nx][ny] = per(d1, d2 + 1);
q.pf({per(nx, ny), dist[nx][ny]});
}
}
}
else{
FOR(i,0,3){
int nx = x + dx[i], ny = y + dy[i];
if (inb(nx, ny) && (eq(dist[nx][ny], per(-1, -1)) || grt(dist[nx][ny], per(d1 + 1, 1 - k)))){
dist[nx][ny] = per(d1 + 1, 1 - k);
q.pb({per(nx, ny), dist[nx][ny]});
}
if (inb(nx, ny) && a[nx][ny] == '.' && (eq(dist[nx][ny], per(-1, -1)) || grt(dist[nx][ny], per(d1, 0)))){
dist[nx][ny] = per(d1, 0);
q.pf({per(nx, ny), dist[nx][ny]});
}
}
}
}
cout << dist[ex][ey].F;
return 0;
}
