#include<iostream>
#include<cstdio>
#include<queue>
#define N 13000000
#define inf 1e9
using namespace std;
int read()
{
    char c=0;
    int sum=0;
    while (c<'0'||c>'9') c=getchar();
    while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
    return sum;
}
struct reads
{
    int num,data;
};
int r,c,n,x1,y1,x2,y2,dis[N+1],rt[N+1],rt2[N+1],ans;
char st[N+1];
bool used[N+1];
int F(int x,int y)
{
    return (x-1)*(c+1)+y;
}
int find(int x)
{
    if (rt[x]==x) return x;
    return rt[x]=find(rt[x]);
}
void unionn(int x,int y)
{
    rt[x]=y;
    return;
}
int find2(int x)
{
    if (rt2[x]==x) return x;
    return rt2[x]=find2(rt2[x]);
}
void unionn2(int x,int y)
{
    rt2[x]=y;
    return;
}
void bfs()
{
    int sx,sy,top,sl,sr;
    queue<int>q0;
    queue<int>q1;
    q0.push(F(x1,y1)),dis[F(x1,y1)]=0;
    while (!q0.empty()||!q1.empty())
    {
	if (q1.empty()||(!q0.empty()&&dis[q0.front()]<dis[q1.front()])) top=q0.front(),q0.pop();
	else top=q1.front(),q1.pop();
	if (used[top]) continue;
	used[top]=1,sx=(top-1)/(c+1)+1,sy=(top+c)%(c+1)+1;
	if (sx-1>=1&&st[F(sx-1,sy)]=='.'&&dis[F(sx-1,sy)]>dis[top]) dis[F(sx-1,sy)]=dis[top],q0.push(F(sx-1,sy));
	if (sx+1<=r&&st[F(sx+1,sy)]=='.'&&dis[F(sx+1,sy)]>dis[top]) dis[F(sx+1,sy)]=dis[top],q0.push(F(sx+1,sy));
	if (sy-1>=1&&st[F(sx,sy-1)]=='.'&&dis[F(sx,sy-1)]>dis[top]) dis[F(sx,sy-1)]=dis[top],q0.push(F(sx,sy-1));
	if (sy+1<=c&&st[F(sx,sy+1)]=='.'&&dis[F(sx,sy+1)]>dis[top]) dis[F(sx,sy+1)]=dis[top],q0.push(F(sx,sy+1));
	if (sx-n>=1)
	{
	    sl=max(sy-n+1,1),sr=min(sy+n-1,c);
	    for (int i=find(F(sx-n,sl));i<=F(sx-n,sr);i=find(i+1))
	    {
		if (dis[i]>dis[top]+1) dis[i]=dis[top]+1,q1.push(i);
		unionn(i,find(i+1));
	    }
	}
	if (sx+n<=r)
	{
	    sl=max(sy-n+1,1),sr=min(sy+n-1,c);
	    for (int i=find(F(sx+n,sl));i<=F(sx+n,sr);i=find(i+1))
	    {
		if (dis[i]>dis[top]+1) dis[i]=dis[top]+1,q1.push(i);
		unionn(i,find(i+1));
	    }
	}
	if (sy-n>=1)
	{
	    sl=max(sx-n+1,1),sr=min(sx+n-1,r);
	    for (int i=find2(F(sl,sy-n));i<=F(sr,sy-n);i=find2(i+c+1))
	    {
		if (dis[i]>dis[top]+1) dis[i]=dis[top]+1,q1.push(i);
		unionn2(i,find2(i+c+1));
	    }
	}
	if (sy+n<=c)
	{
	    sl=max(sx-n+1,1),sr=min(sx+n-1,r);
	    for (int i=find2(F(sl,sy+n));i<=F(sr,sy+n);i=find2(i+c+1))
	    {
		if (dis[i]>dis[top]+1) dis[i]=dis[top]+1,q1.push(i);
		unionn2(i,find2(i+c+1));
	    }
	}
    }
    return;
}
int main()
{
    r=read(),c=read(),n=read(),x1=read(),y1=read(),x2=read(),y2=read();
    for (int i=1;i<=(r+1)*(c+1);++i) rt[i]=rt2[i]=i,dis[i]=inf;
    for (int i=1;i<=r;++i)
	for (int j=1;j<=c;++j)
	    cin>>st[F(i,j)];
    bfs(),ans=dis[F(x2,y2)];
    for (int i=1;i<=r;++i)
	for (int j=1;j<=c;++j)
	    if ((abs(i-x2)<=n&&abs(j-y2)<=n-1)||(abs(i-x2)<=n-1&&abs(j-y2)<=n))
		ans=min(ans,dis[F(i,j)]+1);
    printf("%d\n",ans);
    return 0;
}