//clear adj and visited vector declared globally after each test case
//check for long long overflow
//while adding and subs check if mod becomes -ve
//while using an integer directly in a builtin function add ll
//Mod wale question mein last mein if dalo ie. Ans<0 then ans+=mod;
//Dont keep array name as size or any other key word

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
//#define int long long
#define IOS std::ios::sync_with_stdio(false); cin.tie(NULL);cout.tie(NULL);cout.precision(dbl::max_digits10);
#define pb push_back
#define mod 1000000007 //998244353
#define lld long double
#define mii map<int, int>
#define mci map<char, int>
#define msi map<string, int>
#define pii pair<int, int>
#define ff first
#define ss second 
#define all(x) (x).begin(), (x).end()
#define rep(i,x,y) for(int i=x; i<y; i++)    
#define fill(a,b) memset(a, b, sizeof(a))
#define vi vector<int>
#define setbits(x) __builtin_popcountll(x)
#define print2d(dp,n,m) for(int i=0;i<=n;i++){for(int j=0;j<=m;j++)cout<<dp[i][j]<<" ";cout<<"\n";}
typedef std::numeric_limits< double > dbl;
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> indexed_set;
const long long N=100005, INF=(int)1e9;
lld pi=3.1415926535897932;
int lcm(int a, int b)
{
    int g=__gcd(a, b);
    return a/g*b;
}
int power(int a, int b, int p)
    {
        if(a==0)
        return 0;
        int res=1;
        a%=p;
        while(b>0)
        {
            if(b&1)
            res=(res*a)%p;
            b>>=1;
            a=(a*a)%p;
        }
        return res;
    }
vector <int> v[N], temp;
int ch[N],n;
void dfs(int u, int p)
{
    ch[u]=1;
    for(auto to:v[u])
    {
        if(to==p)
        continue;
        dfs(to, u);
        ch[u]+=ch[to];
        //cout<<u<<" "<<to<<" "<<ch[to]<<" "<<n-ch[to]<<"\n";
        temp.pb((ch[to]*(n-ch[to])));
    }
    return;
}
int h,w;
string s[1001];
int dp[1002][1002];
int dx[]={1, -1, 0, 0};
int dy[]={0, 0, 1, -1};
bool valid(int x, int y)
{
    if(x>=0&&x<h&&y>=0&&y<w&&s[x][y]=='.')
    return true;
    return false;
}
int32_t main()
{
    IOS;
    cin>>h>>w;
    int x1,x2,y1,y2;
    cin>>x1>>y1>>x2>>y2;
    x1--;x2--;y1--;y2--;
    for(int i=0;i<h;i++)
    cin>>s[i];
    rep(i,0,h)
    rep(j,0,w)
    dp[i][j]=INF;
    deque <pair<pii, int> > q;
    vector <pii> temp;
    for(int i=-2;i<3;i++)
    {
        for(int j=-2;j<3;j++)
        {
            if(i!=0||j!=0)
            {
                temp.pb({i, j});
                //cout<<i<<" "<<j<<"\n";
            }
        }
    }
    q.push_front({{x1, y1}, 0});
    dp[x1][y1]=0;
    while(!q.empty())
    {
        pair<pii, int> p=q.front();
        int x=p.ff.ff,y=p.ff.ss;
        q.pop_front();
        for(int i=0;i<4;i++)
        {
            if(valid(x+dx[i], y+dy[i])&&dp[x+dx[i]][y+dy[i]]>p.ss)
            {
                dp[x+dx[i]][y+dy[i]]=p.ss;
                q.push_front({{x+dx[i], y+dy[i]}, p.ss});
            }
        }
        for(int i=0;i<24;i++)
        {
            if(valid(x+temp[i].ff, y+temp[i].ss)&&dp[x+temp[i].ff][y+temp[i].ss]>(p.ss+1))
            {
                dp[x+temp[i].ff][y+temp[i].ss]=p.ss+1;
                q.push_back({{x+temp[i].ff, y+temp[i].ss}, p.ss+1});
            }
        }
    }
    if(dp[x2][y2]==INF)
    cout<<-1;
    else
    cout<<dp[x2][y2];
}

Measured memory_bytes: 10964