#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pll pair<long long, long long>
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define endl '\n'
#define ld long double
#define sz(x) static_cast<int>((x).size())
#define i5 tuple<int,int,int,int,int>
#define all(x) x.begin(), x.end()
#define iiii tuple<int, int,int,int>
signed main(){
int r, c, n;cin>>r>>c>>n;
int sr,sc,gr,gc;cin>>sr>>sc>>gr>>gc;
vector<vector<bool>> mat(r+2, vector<bool>(c+2, 0)), vis0(r+2, vector<bool>(c+2, 0)), vis1(r+2, vector<bool>(c+2, 0));
vector<vector<int>> d(r+2, vector<int>(c+2, -1));
for(int i=1;i<=r;i++){
for(int j=1;j<=c;j++){
char c;cin>>c;
if(c=='.')mat[i][j]=1;
}
}
vector<pll> cur;
cur.pb({sr, sc});
d[sr][sc]=0;
int dir[4][2]={{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
auto out=[&](int x, int y)->bool{return ((x < 1) or (x > r) or (y < 1) or (y > c));};
int cd=0;
while(!cur.empty()){
vector<pll> b;
// do 0-1 bfs from every cell in b
for (auto [x, y] : cur){
queue<pll> q;
q.push({x, y});
vis0[x][y]=true;
while(!q.empty()){
auto [i, j] = q.front(); q.pop();
//printf("%lld %lld \n", i, j);
for(int k=0;k<4;k++){
int di=dir[k][0], dj=dir[k][1];
int ni=i+di, nj=j+dj;
//printf("di %lld dj %lld, ni %lld nj %lld\n", di, dj, ni, nj);
if (out(ni, nj) or vis0[ni][nj]){
continue;
}
if (!mat[ni][nj]) {
b.pb({ni, nj});
d[ni][nj]=d[i][j]+1;
}
else {
q.push({ni, nj});
d[ni][nj]=d[i][j];
}
vis0[ni][nj]=true;
}
}
}
/*printf("cd %lld, border cells are \n", cd);
for(auto [i, j] : b){
printf("(%lld, %lld) ", i, j);
}
cout<<endl;*/
for(int k=0;k<4;k++){
int di=dir[k][0], dj=dir[k][1];
vector<pll> nw, lay=b;
for(int t=0;t<n-1;t++){
vector<pll> nxtlay;
for(auto [i, j] : lay){
int ni=i+di, nj=j+dj;
if(out(ni, nj) or vis0[ni][nj])continue;
vis0[ni][nj]=true;
d[ni][nj]=cd+1;
nw.pb({ni, nj});
nxtlay.pb({ni, nj});
}
swap(nxtlay, lay);
}
b.insert(b.end(),all(nw));
}
swap(cur, b);
cd++;
}
cout<<d[gr][gc];
}
