#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
     
#define fast { ios :: sync_with_stdio(false); cin.tie(0); cout.tie(0); }
#define pb push_back
#define ll long long
#define ld long double
     
#define vi vector<int>
#define vl vector<long>
#define vll vector<long long>
     
#define infi INT_MAX
#define infl LONG_LONG_MAX
#define infd LDBL_MAX
#define f(i,a,b) for(ll i=a;i<b;i++)
#define fi(i,a,b) for(ll i=(b-1);i>=a;i--)
#define F first
#define S second
#define G(a,b) get<a>(b)
#define MP make_pair
#define MT make_tuple
#define pll pair<ll,ll> 
#define endl "\n"
#define ALL(v) v.begin(),v.end()
#define nl cout<<"\n";
#define pr(x) cout<<x;
#define pr1(x) cout<<x<<" ";
#define pr2(x,y) cout<<x<<" "<<y;
#define pr4(x,y,z,w) cout<<x<<" "<<y<<" "<<z<<" "<<w;
#define deb printf("***************************************************************************************\n");
#define moshi printf("moshi moshi ! \n");
#define hi printf("hi ! \n");
#define bye printf("bye bye ! \n");
#define o_set(ll) tree<ll, null_type,less<ll>, rb_tree_tag,tree_order_statistics_node_update>
#define number_of_set_bits  __builtin_popcountll  
const ld PI=3.1415926535897932384626433; 


//template<typename T>
//#define o_set(T) tree<T, null_type,less<T>, rb_tree_tag,tree_order_statistics_node_update>
//member functions :
//1. order_of_key(k) : number of elements strictly lesser than k
//2. find_by_order(k) : k-th element in the set
     
     
//const ll N=1e6+7;
ll p=1e9+7;
//ll fac[N];
     
ll gcd(ll a, ll b) 
{ 
   if (a == 0) return b; 
   return gcd(b % a, a); 
} 
     
inline ll ceil(ll a,ll b)
{
   return (a+b-1)/b;
}
     
ll max(ll x,ll y,ll z)
{
   return max(x,max(y,z));
}

ll min(ll x,ll y,ll z)
{
   return min(x,min(y,z));
} 
     
     
ll modpro(ll x,ll y,ll z=1)
{
   x%=p;
   y%=p;
   z%=p;
   ll res=(x*y)%p;
   res=(res*z)%p;
   return res;
}
     
ll modadd(ll x,ll y,ll z=0)
{
   x%=p;
   y%=p;
   z%=p;
   ll res=(x+y)%p;
   res=(res+z)%p;
   return res;
}
     
     
ll pow_mod_p(ll a,ll b)
{
   a=a%p;
   ll res=1;
   while(b>0)
   {
     if(b&1) res=(res*a)%p;
     b=b>>1;
     a=(a*a)%p;
   }
   return res;
}
     
inline ll mod_inv(ll x)
{
   return pow_mod_p(x,p-2);
}
    
     
// Don't forget to set fac[0]=1
/*ll nCr(ll x,ll y)
{
   if(x<y) return 0;
   ll res=fac[x];
   ll den=(fac[y]*fac[x-y])%p;
   ll deni=mod_inv(den);
   res=(res*deni)%p;
   return res;
}*/



ll is_set(ll a,ll i)
{
   if( ( a & ((ll)1<<i) ) == 0 ) return 0;
   else return 1;
}  
    


//  Comparator should follow :
//  1: x<=y or y<=x uniquely 
//  2: Transitivity : a<=b and b<=c implies a<=c
//  3: Anti-Symmetry: a<=b and b<=a implies a=b
// return 1 to put x before y in sorted order 
inline bool comp(pll &x,pll &y)
{
   if(x.F<y.F) return 1;
   else if(x.F==y.F)
   {
      if(x.S>y.S) return 1;
      else return 0;
   }
   return 0;
}
     
     
struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }     
    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};
     
// resize : str.resize(new_size)   new size <= old size
     
// for Vector :
// lower_bound(starting iterator , iterator next to end , value)  :  iterator to first element greater than or equal to value
// upper_bound(starting iterator , iterator next to end , value)  :  iterator to first element strictly greater than value
     
// For Set :      s.lower_bound(value)
// if no such element exists they return  vector.end() or s.end()
     
     
// x bits : [x-1 , x-2 , .... , 1(1st bit) , 0(0th bit)] =>   leftmost 1 at 2^(x-1)    max number that can be represented : 2^(x) -1
// 63 bits is greater than 10^18
     
// 1<<x  :  2 ^ x  (left shift)
 
// Min heap :  priority_queue < ll , vector<ll>, greater<ll> > q  
// Max heap :  priority_queue < ll > q
    // Set in descending order  :   set< ll,greater <ll> >
     
     
// While debugging : 
// 1 : check if array size is correct  :  It may give unexpected results
// 2 : check if you have swapped i and j at some part of program
// 3 : for string check if you are trying to acces  index = -1 


// Bitwise Tricks :
// 1 : While using 1<<i  use (ll)1<<i  because in former one "1" is considered as int
// 2 : To flip first k-bits of a number :  x xor (2^k-1)  or x ^ (((ll)1<<k)-1)  : 2^k-1 is the largest number of k bits
// 3 : To flip k-th bit (0-based)  :  x xor (2^k)  or  x ^ ((ll)1<<k)
// 4 : To set k-th bit (0-based)   :  x or (2^k)   or  x | ((ll)1<<k)
// 5 : To un-set k-th bit (0-based)   :  x & (~ ((ll)1<<k) )


// To prove Greedy :
// 1 : Optimal Choice at each step 
// 2 : Exchange Argument
// 3 : Find a lower or upper bound on answer and then construct an answer for that bound
// 4 : Find properties which Optimal Solution must satisfy ( This can be useful to deduce form of Optimal answer)

// Erase one occurrence in multiset : it=s.find(element)   s.erase(it) 
// putchar('a'+j) : to print (j+1)th character 
// getline(cin,str) : To input string until newline
    

void lps(string &pp,ll *lps)
{
   ll xx=pp.length();
   //ll lps[xx]={};
   f(i,1,xx)
   {
       ll j=lps[i-1];
       while(j>0 && pp[j]!=pp[i]) j=lps[j-1];
       if(pp[i]==pp[j]) j++;
       lps[i]=j;
   }
}

    
// Remember to take input string as  getline(cin,s)
void stoi(string &s,vll &v)
{
   stringstream str(s);
   ll x;
   while(str>>x)
   {
       v.pb(x);
   }
}




void Miden(ll **p1,ll n)
{
    ll (*x)[n]=(ll(*)[n]) p1;
    f(i,0,n)
    {
        f(j,0,n)
        {
            x[i][j]=0;
        }
        x[i][i]=1;
    }
    return;
}
 
void Mmult(ll **p1,ll **p2,ll **ans,ll x,ll y,ll z,ll m)
{
    ll (*a)[y]=(ll (*)[y])p1;
    ll (*b)[z]=(ll (*)[z])p2;
    ll (*c)[z]=(ll (*)[z])ans;
    f(i,0,x)
    {
        f(j,0,z)
        {
            c[i][j]=0;
            f(k,0,y)
            {
                c[i][j]+=a[i][k]*b[k][j];
                c[i][j]%=m;
            }
        }
    }
    return;
}
 
void Mpow(ll **p1,ll **ans,ll n,ll y,ll m)
{
    if(y==0)
    {
        Miden(ans,n);
        return;
    }
    ll t[n][n];
    Mpow(p1,(ll **)t,n,y/2,m);
    ll z[n][n];
    Mmult((ll **)t,(ll **)t,(ll **)z,n,n,n,m);
    if(y%2)
    {
        Mmult((ll **)z,p1,ans,n,n,n,m);
    }
    else
    {
        Miden((ll **)t,n);
        Mmult((ll **)z,(ll **)t,ans,n,n,n,m);
    }
    return;
}


ll n,m,k,sx,sy,x2,y2;
const ll N=1003*1003;
char s[N];

ll dx[4]={0,0,1,-1};
ll dy[4]={1,-1,0,0};

bool visited[4][N];
ll dist[N];

inline bool is_valid(ll x,ll y)
{
  return (x>=0 && x<n && y>=0 && y<m && s[x*m+y]=='.');
}

void bfs()
{
  f(i,0,n) f(j,0,m) dist[i*m+j]=infl;

  queue<ll>q;
  dist[sx*m+sy]=0;
  q.push(sx*m+sy);


  while(!q.empty())
  {
    ll x=q.front()/m,y=q.front()%m;
    q.pop();

    f(i,0,4)
    {
      ll nx=x+dx[i],ny=y+dy[i];
      f(j,1,k+1)
      {
        if(!is_valid(nx,ny) || dist[nx*m+ny]<=dist[x*m+y] || visited[i][nx*m+ny]) break;
        else 
        {
          visited[i][nx*m+ny]=1;
          dist[nx*m+ny]=dist[x*m+y]+1;
          q.push(nx*m+ny);
        }

        nx+=dx[i],ny+=dy[i]; 
      }
    }
  }
}


void func()
{      
  cin>>n>>m>>k;
  cin>>sx>>sy>>x2>>y2;
  sx--;
  sy--;
  x2--;
  y2--;
  f(i,0,n) f(j,0,m) cin>>s[i*m+j];

  bfs();
  if(dist[x2*m+y2]==infl) cout<<"-1\n";
  else cout<<dist[x2*m+y2]<<endl;
}   
     
     
int main() 
{
    fast
    //#ifndef ONLINE_JUDGE
    //freopen("input.txt", "r", stdin);
    //freopen("output.txt", "w", stdout);
    //#endif // ONLINE_JUDGE
        
     
    ll ntc=1;
    //cin>>ntc;
     
    f(i,1,ntc+1)
    {
      //cout<<"Case #"<<i<<": ";
      func();
    }     
    return 0;
}

Measured memory_bytes: 16248