Language: C++

/**
 * @Author : Gaurang_Kothiya
**/

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>  
#include <ext/pb_ds/tree_policy.hpp> 
#include <functional>
#include <bitset>
#include <cstdint>
#include <initializer_list>
 
using namespace std;
using namespace __gnu_pbds;  

#define data_set(type) tree<type,null_type,less<type>,rb_tree_tag,tree_order_statistics_node_update>
#define speed ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
//#define int long long int
#define ld long double
#define f(i,x,n) for(int i=x;i<=n;i++)
#define fe(x,v)   for(auto &x :v)
#define nf(i,x,n) for(int i=n;i>=x;i--)
#define all(a)   a.begin(),a.end()
#define rall(a)  a.rbegin(),a.rend()
#define ook(num) order_of_key(num)
#define fbo(num) find_by_order(num)
#define gcd(a,b) __gcd(a,b)
#define bits(n) __builtin_popcountll(n)
#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define RE rend()
#define RB rbegin()
#define B begin()
#define E end()
#define acc(v, x) accumulate(all(v), x)
#define p(a,b) pair<a,b>
#define F first
#define S second
#define sz size()
#define v(x) vector<x>
#define m(a,b) map<a,b>
#define u_m(a,b) unordered_map<a,b>
#define mm(a,b) multimap<a,b>
#define s(a) set<a>
#define us(a) unordered_set<a>
#define ms(a) multiset<a>
#define maxy __LONG_LONG_MAX__
#define miny INT_MIN
#define PI 3.14159265358979323846

const int inf= 1e9 +1;
const int inf64= 1e18 -1;
const int MOD= 1e9 +7;
const int MOD2= 998244353;

int n,m;
int x1,y1,x2,y2;
char a[1003][1003];
m(p(int,int),bool) v1,v2;
v(p(int,int)) vec1,vec2;

bool range(int x,int y)
{
	return (x>=1 && x<=n && y>=1 && y<=m);
}

void dfs(int x,int y,m(p(int,int),bool) &vis,v(p(int,int)) &vec)
{
	vis[{x,y}]=true;
	vec.pub({x,y});
	if(range(x+1,y))
	{
		if(a[x+1][y]=='.' && vis[{x+1,y}]==false) dfs(x+1,y,vis,vec);
	}
	if(range(x-1,y))
	{
		if(a[x-1][y]=='.' && vis[{x-1,y}]==false) dfs(x-1,y,vis,vec);
	}
	if(range(x,y+1))
	{
		if(a[x][y+1]=='.' && vis[{x,y+1}]==false) dfs(x,y+1,vis,vec);
	}
	if(range(x,y-1))
	{
		if(a[x][y-1]=='.' && vis[{x,y-1}]==false) dfs(x,y-1,vis,vec);
	}
}


void Solve()
{
	cin>>n>>m;
	cin>>x1>>y1>>x2>>y2;
	memset(a,'#',sizeof(a));
	f(i,1,n)
	{
		f(j,1,m) cin>>a[i][j];
	}
	dfs(x1,y1,v1,vec1);
	dfs(x2,y2,v2,vec2);
	if(v2[{x1,y1}])
	{
		cout<<"0";
		return;
	}
	
	int ans=99;
	
	fe(p1,vec1)
	{
		fe(p2,vec2)
		{
			int dif= max(abs(p1.F-p2.F),abs(p1.S-p2.S));
			if(dif<=2)
			{
				ans=min(ans,dif);
			}
		}
	}
	if(ans==99) cout<<"-1";
	else cout<<ans;
}
 
signed main() 
{
	speed		

	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);	

	int q=1;
	//cin>>q;
	
	while(q--)
	Solve();
		
	return 0;
} 

Compiler output:
a.cc:54:23: warning: overflow in conversion from 'double' to 'int' changes value from '1.0e+18' to '2147483647' [-Woverflow]
   54 | const int inf64= 1e18 -1;
      |                  ~~~~~^~
a.cc:59:8: error: 'int y1' redeclared as different kind of entity
   59 | int x1,y1,x2,y2;
      |        ^~
In file included from /usr/include/features.h:523,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/os_defines.h:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/c++config.h:683,
                 from /usr/include/c++/14/cassert:43,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:33,
                 from a.cc:5:
/usr/include/x86_64-linux-gnu/bits/mathcalls.h:257:1: note: previous declaration 'double y1(double)'
  257 | __MATHCALL (y1,, (_Mdouble_));
      | ^~~~~~~~~~
a.cc: In function 'void Solve()':
a.cc:95:16: error: no match for 'operator>>' (operand types are 'std::basic_istream<char>::__istream_type' {aka 'std::basic_istream<char>'} and 'double(double) noexcept')
   95 |         cin>>x1>>y1>>x2>>y2;
      |         ~~~~~~~^~~~
      |            |     |
      |            |     double(double) noexcept
      |            std::basic_istream<char>::__istream_type {aka std::basic_istream<char>}
In file included from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/istream:170:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  170 |       operator>>(bool& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:170:7: note:   conversion of argument 1 would be ill-formed:
a.cc:95:18: error: cannot bind non-const lvalue reference of type 'bool&' to a value of type 'double (*)(double) noexcept'
   95 |         cin>>x1>>y1>>x2>>y2;
      |                  ^~
/usr/include/c++/14/istream:174:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  174 |       operator>>(short& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:174:7: note:   conversion of argument 1 would be ill-formed:
a.cc:95:18: error: invalid conversion from 'double (*)(double) noexcept' to 'short int' [-fpermissive]
   95 |         cin>>x1>>y1>>x2>>y2;
      |                  ^~
      |                  |
      |                  double (*)(double) noexcept
a.cc:95:18: error: cannot bind rvalue '(short int)y1' to 'short int&'
/usr/include/c++/14/istream:177:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  177 |       operator>>(unsigned short& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:177:7: note:   conversion of argument 1 would be ill-formed:
a.cc:95:18: error: invalid conversion from 'double (*)(double) noexcept' to 'short unsigned int' [-fpermissive]
   95 |         cin>>x1>>y1>>x2>>y2;
      |                  ^~
      |                  |
      |                  double (*)(double) noexcept
a.cc:95:18: error: cannot bind rvalue '(short unsigned int)y1' to 'short unsigned int&'
/usr/include/c++/14/istream:181:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  181 |       operator>>(int& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:181:7: note:   conversion of argument 1 would be ill-formed:
a.cc:95:18: error: invalid conversion from 'double (*)(double) noexcept' to 'int' [-fpermissive]
   95 |         cin>>x1>>y1>>x2>>y2;
      |                  ^~
      |                  |
      |                  double (*)(double) noexcept
a.cc:95:18: error: cannot bind rvalue '(int)y1' to 'int&'
/usr/include/c++/14/istream:184:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  184 |       operator>>(unsigned int& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:184:7: note:   conversion of argument 1 would be ill-formed:
a.cc:95:18: error: invalid conversion from 'double (*)(double) noexcept' to 'unsigned int' [-fpermissive]
   95 |         cin>>x1>>y1>>x2>>y2;
      |                  ^~
      |                  |
      |                  double (*)(double) noexcept
a.cc:95:18: error: cannot bind rvalue '(unsigned int)y1' to 'unsigned int&'
/usr/include/c++/14/istream:188:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  188 |       operator>>(long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:188:7: note:   conversion of argument 1 would be ill-formed:
a.cc:95:18: error: invalid conversion from 'double (*)(double) noexcept' to 'long int' [-fpermissive]
   95 |         cin>>x1>>y1>>x2>>y2;
      |                  ^~
      |                  |
      |                  double (*)(double) noexcept
a.cc:95:18: error: cannot bind rvalue '(long int)y1' to 'long int&'
/usr/include/c++/14/istream:192:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  192 |       operator>>(unsigned long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:192:7: note:   conversion of argument 1 would be ill-formed:
a.cc:95:18: error: invalid conversion from 'double (*)(double) noexcept' to 'long unsigned int' [-fpermissive]
   95 |         cin>>x1>>y1>>x2>>y2;
      |                  ^~
      |                  |
      |                  double (*)(double) noexcept
a.cc:95:18: error: cannot bind rvalue '(long unsigned int)y1' to 'long unsigned int&'
/usr/include/c++/14/istream:199:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  199 |       operator>>(long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:199:7: note:   conversion of argument 1 would be ill-formed:
a.cc:95:18: error: invalid conversion from 'double (*)(double) noexcept' to 'long long int' [-fpermissive]
   95 |         cin>>x1>>y1>>x2>>y2;
      |                  ^~
      |                  |
      |                  double (*)(double) noexcept
a.cc:95:18: error: cannot bind rvalue '(long long int)y1' to 'long long int&'
/usr/include/c++/14/istream:203:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  203 |       operator>>(unsigned long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:203:7: note:   conversion of argument 1 would be ill-formed:
a.cc:95:18: error: invalid conversion from 'double (*)(double) noexcept' to 'long long unsigned int' [-fpermissive]
   95 |         cin>>x1>>y1>>x2>>y2;
      |                  ^~
      |                  |
      |                  double (*)(double) noexcept
a.cc:95:18: error: cannot bind rvalue '(long long unsigned int)y1' to 'long long unsigned int&'
/usr/include/c++/14/istream:328:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(void*&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  328 |       operator>>(void*& __p)
      |       ^~~~~~~~
/usr/include/c++/14/istream:328:7: note:   conversion of argument 1 would be ill-formed:
a.cc:95:18: error: invalid conversion from 'double (*)(double) noexcept' to 'void*' [-fpermissive]
   95 |         cin>>x1>>y1>>x2>>y2;
      |                  ^~
      |                  |
      |                  double (*)(double) noexcept
a.cc:95:18: error: cannot bind rvalue '(void*)y1' to 'void*&'
/usr/include/c++/14/istream:122:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(__istream_type& (*)(__istream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  122 |       operator>>(__istream_type& (*__pf)(__istream_type&))
      |       ^~~~~~~~
/usr/include/c++/14/istream:122:7: note:   conversion of argument 1 would be ill-formed:
a.cc:95:18: error: invalid conversion from 'double (*)(double) noexcept' to 'std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&)' {aka 'std::basic_istream<char>& (*)(std::basic_istream<char>&)'} [-fpermissive]
   95 |         cin>>x1>>y1>>x2>>y2;
      |                  ^~
      |                  |
      |                  double (*)(double) noexcept
/usr/include/c++/14/istream:126:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(__ios_type& (*)(__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>; __ios_type = std::basic_ios<char>]' (near match)
  126 |       operator>>(__ios_type& (*__pf)(__ios_type&))
      |       ^~~~~~~~
/usr/include/c++/14/istream:126:7: note:   conversion of argument 1 would be ill-formed:
a.cc:95:18: