#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef __int128 lll;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pld;
#define MAX 9223372036854775807LL
#define MIN -9223372036854775807LL
#define INF 0x3f3f3f3f3f3f3f3f
#define fi first
#define se second
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); cout << fixed; cout.precision(10);
#define sp << " "
#define en << "\n"
#define compress(v) sort(v.begin(), v.end()), v.erase(unique(v.begin(), v.end()), v.end())
ll R, C, N;
ll sx, sy;
ll ex, ey;
vector<string> a;
vector< vector<ll> > chk;
vector<ll> tmp;
string all;
vector<pll> now;
ll dx[] = {-1, 1, 0, 0};
ll dy[] = {0, 0, -1, 1};
ll T;
void Wbfs(void)
{
queue<pll> q;
for(auto &i : now)
q.push(i);
while(!q.empty())
{
pll qq = q.front();
q.pop();
for(ll d = 0 ; d < 4 ; d++)
{
ll nx = qq.fi + dx[d];
ll ny = qq.se + dy[d];
if(nx < 0 || ny < 0 || nx >= R || ny >= C)
continue;
if(a[nx][ny] == '#' || chk[nx][ny])
continue;
chk[nx][ny] = T;
now.push_back({nx, ny});
q.push({nx, ny});
}
}
}
int main(void)
{
fastio
cin >> R >> C >> N;
cin >> sx >> sy;
cin >> ex >> ey;
sx--, sy--;
ex--, ey--;
for(ll i = 0 ; i < R ; i++)
{
cin >> all;
a.push_back(all);
}
for(ll i = 0 ; i < C ; i++)
tmp.push_back(0);
for(ll i = 0 ; i < R ; i++)
chk.push_back(tmp);
T = 1;
chk[sx][sy] = T;
now.push_back({sx, sy});
Wbfs();
while(1)
{
if(chk[ex][ey])
{
cout << chk[ex][ey] - 1;
return 0;
}
T++;
vector<pll> tmp2;
for(auto &i : now)
{
for(ll d = 0 ; d < 4 ; d++)
{
ll nx = i.fi + dx[d];
ll ny = i.se + dy[d];
if(nx < 0 || ny < 0 || nx >= R || ny >= C)
continue;
if(chk[nx][ny] || a[nx][ny] == '.')
continue;
chk[nx][ny] = T;
tmp2.push_back({nx, ny});
}
}
now = tmp2;
for(auto &i : tmp2)
{
for(ll d = 1 ; d < N ; d++)
{
ll nx = i.fi - d;
ll ny = i.se;
if(nx < 0 || nx >= R)
continue;
if(chk[nx][ny])
break;
chk[nx][ny] = T;
now.push_back({nx, ny});
}
for(ll d = 1 ; d < N ; d++)
{
ll nx = i.fi + d;
ll ny = i.se;
if(nx < 0 || nx >= R)
continue;
if(chk[nx][ny])
break;
chk[nx][ny] = T;
now.push_back({nx, ny});
}
}
tmp2 = now;
for(auto &i : tmp2)
{
for(ll d = 1 ; d < N ; d++)
{
ll nx = i.fi;
ll ny = i.se - d;
if(ny < 0 || ny >= C)
continue;
if(chk[nx][ny])
break;
chk[nx][ny] = T;
now.push_back({nx, ny});
}
for(ll d = 1 ; d < N ; d++)
{
ll nx = i.fi;
ll ny = i.se + d;
if(ny < 0 || ny >= C)
continue;
if(chk[nx][ny])
break;
chk[nx][ny] = T;
now.push_back({nx, ny});
}
}
Wbfs();
}
return 0;
}
