# include <iostream>
# include <vector>
# include <queue>
using namespace std;
const int MAX=6e6+11,INF=1e9;
int n,m,K;
pair<int,int> S,T;
vector<char> tab[MAX];
vector<int> dist[MAX];
int adj[4][2]={{1,0},{0,1},{-1,0},{0,-1}};
bool in(int x, int y)
{
return x>=1 and x<=n and y>=1 and y<=m;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin>>n>>m>>K;
for(int i=0;i<=n+1;i++)
{
tab[i].resize(m+2,'.');
dist[i].resize(m+2,INF);
}
cin>>S.first>>S.second;
cin>>T.first>>T.second;
for(int i=1;i<=n;i++)
{
for(int j=1;j<=m;j++) cin>>tab[i][j];
}
queue<pair<int,int>> q1;
dist[S.first][S.second]=0;
q1.push(S);
while(q1.size()>0)
{
queue<pair<pair<int,int>,pair<int,int>>> q2;
while(q1.size()>0)
{
int x=q1.front().first,y=q1.front().second;
q1.pop();
//cout<<"->"<<x<<" "<<y<<"\n";
for(int i=0;i<4;i++)
{
int x2=x+adj[i][0];
int y2=y+adj[i][1];
if(!in(x2,y2)) continue;
if(tab[x2][y2]=='#')
{
if(dist[x2][y2]==INF)
{
dist[x2][y2]=dist[x][y]+1;
q2.push({{x2,y2},{1,1}});
}
}
else
{
if(dist[x2][y2]==INF)
{
dist[x2][y2]=dist[x][y];
q1.push({x2,y2});
}
}
}
}
while(q2.size()>0)
{
int x=q2.front().first.first,y=q2.front().first.second;
int hor=q2.front().second.first,ver=q2.front().second.second;
q2.pop();
q1.push({x,y});
for(int i=0;i<4;i++)
{
int x2=x+adj[i][0];
int y2=y+adj[i][1];
int hor2=hor+abs(adj[i][0]);
int ver2=ver+abs(adj[i][1]);
if(!in(x2,y2) or hor2>K or ver2>K) continue;
if(dist[x2][y2]==INF)
{
dist[x2][y2]=dist[x][y];
q2.push({{x2,y2},{hor2,ver2}});
}
}
}
}
cout<<dist[T.first][T.second]<<"\n";
return 0;
}
