Problem:
Score : 400 points

Problem Statement

A maze is composed of a grid of H \times W squares - H vertical, W horizontal.

The square at the i-th row from the top and the j-th column from the left - (i,j) - is a wall if S_{ij} is # and a road if S_{ij} is ..

There is a magician in (C_h,C_w). He can do the following two kinds of moves:

Move A: Walk to a road square that is vertically or horizontally adjacent to the square he is currently in.

Move B: Use magic to warp himself to a road square in the 5\times 5 area centered at the square he is currently in.

In either case, he cannot go out of the maze.

At least how many times does he need to use the magic to reach (D_h, D_w)?

Constraints

1 \leq H,W \leq 10^3

1 \leq C_h,D_h \leq H

1 \leq C_w,D_w \leq W

S_{ij} is # or ..

S_{C_h C_w} and S_{D_h D_w} are ..

(C_h,C_w) \neq (D_h,D_w)

Input

Input is given from Standard Input in the following format:

H W
C_h C_w
D_h D_w
S_{11}\ldots S_{1W}
\vdots
S_{H1}\ldots S_{HW}

Output

Print the minimum number of times the magician needs to use the magic. If he cannot reach (D_h,D_w), print -1 instead.

Sample Input 1

4 4
1 1
4 4
..#.
..#.
.#..
.#..

Sample Output 1

1

For example, by walking to (2,2) and then using the magic to travel to (4,4), just one use of magic is enough.

Note that he cannot walk diagonally.

Sample Input 2

4 4
1 4
4 1
.##.
####
####
.##.

Sample Output 2

-1

He cannot move from there.

Sample Input 3

4 4
2 2
3 3
....
....
....
....

Sample Output 3

0

No use of magic is needed.

Sample Input 4

4 5
1 2
2 5
#.###
####.
#..##
#..##

Sample Output 4

2

Solution in C# (.NET Core 3.1.201) (judge verdict: Time Limit Exceeded)

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Runtime.Intrinsics.X86;
using System.Text;
using static Solve.Methods;
using static Solve.Input;
using static Solve.Output;
using static Solve.Solver;
using static System.Math;

namespace Solve
{
    public partial class Solver
    {
        public void Main() {
            var (H, W) = Int;
            var (Ch, Cw) = Int;
            var (Dh, Dw) = Int;
            Ch--;
            Cw--;
            Dh--;
            Dw--;
            var grid = new char[H, W];
            for (int i = 0; i < H; i++) {
                var s = String.r;
                for (int j = 0; j < W; j++) grid[i, j] = s[j];
            }

            var dijkstra = new Dijkstra(H * W);
            // i * W + j
            int Convert(int i, int j) => i * W + j;
            bool inMap(int i, int j) => (uint) i < H && (uint) j < W;

            var dxWarp = new []{
                -2, -1, 0, 1, 2,
                -2, -1, 1, 2,
                -2, 2,
                -2, -1, 1, 2,
                -2, -1, 0, 1, 2,
            };
            var dyWarp = new[] {
                -2, -2, -2, -2, -2,
                -1, -1, -1, -1,
                0,  0,
                1, 1,  1, 1,
                2, 2, 2, 2, 2
            };
            

            for (int i = 0; i < H; i++) {
                for (int j = 0; j < W; j++) {
                    if (grid[i, j] == '#') continue;
                    
                    for (int k = 0; k < 4; k++) {
                        int ni = i + dx[k], nj = j + dy[k];
                        if (!inMap(ni, nj) || grid[ni, nj] == '#') continue;
                        dijkstra.Add(Convert(i, j), Convert(ni, nj), 0);
                    }
                    
                    // 5 * 5 の範囲 - 5
                    for (int k = 0; k < 20; k++) {
                        int ni = i + dxWarp[k], nj = j + dyWarp[k];
                        if (!inMap(ni, nj) || grid[ni, nj] == '#') continue;
                        dijkstra.Add(Convert(i, j), Convert(ni, nj), 1);                        
                    }
                }
            }

            var res = dijkstra.Run(Convert(Ch, Cw));
            var ans = res[Convert(Dh, Dw)].Cost;
            print(ans == LINF ? -1 : ans);

        }

        public const int MOD = 1000000007;
    }

    public class PriorityQueue<T> where T : IComparable<T>
    {
        public bool Any() => Count > 0;
        public int Count { get; private set; }
        private readonly bool descendance;
        private T[] data = new T[65536];
        private readonly IComparer<T> comparer;

        public PriorityQueue(bool descendance = false, IComparer<T> comparer = null) =>
            (this.descendance, this.comparer) = (descendance, comparer ?? Comparer<T>.Default);

        ///<remarks>O(1)</remarks>
        public T Top {
            [MethodImpl(256)]
            get {
                Check();
                return data[1];
            }
        }

        /// <remarks>O(log N)</remarks>
        public T Pop() {
            var top = Top;
            var elem = data[Count--];
            int index = 1;
            while (true) {
                if (index << 1 >= Count) {
                    if (index << 1 > Count) break;
                    if (comparer.Compare(elem, data[index << 1]) > 0 ^ descendance) data[index] = data[index <<= 1];
                    else break;
                } else {
                    var nextIndex =
                        comparer.Compare(data[index << 1], data[(index << 1) + 1]) <= 0 ^ descendance
                            ? index << 1
                            : (index << 1) + 1;
                    if (comparer.Compare(elem, data[nextIndex]) > 0 ^ descendance)
                        data[index] = data[index = nextIndex];
                    else break;
                }
            }

            data[index] = elem;
            return top;
        }

        public void Add(T value) => Push(value);

        /// <remarks>O(log N)</remarks>
        public void Push(T value) {
            int index = ++Count;
            if (data.Length == Count) Extend(data.Length * 2);
            while (index >> 1 != 0) {
                if (comparer.Compare(data[index >> 1], value) > 0 ^ descendance)
                    data[index] = data[index >>= 1];
                else break;
            }

            data[index] = value;
        }

        private void Extend(int newSize) {
            var newDatas = new T[newSize];
            data.CopyTo(newDatas, 0);
            data = newDatas;
        }

        private bool Check() => Count > 0 ? true : throw new Exception();
    }
    public interface IEdge
    {
        int To { get; }
        long Cost { get; }
        public void Deconstruct(out int t, out long c) => (t, c) = (To, Cost);
    }

    public interface Graph<EdgeType> where EdgeType : IEdge
    {
        int Length { get; }
        List<EdgeType> this[int i] { get; }
        List<EdgeType>[] Graph { get; }
        void InputGraph(int m, in bool directed, in int offset);
    }

    public readonly struct WeightEdge : IEdge
    {
        public WeightEdge(int to, long cost) => (To, Cost) = (to, cost);
        public int To { get; }
        public long Cost { get; }
    }

    public class WeightGraph : Graph<WeightEdge>
    {
        public WeightGraph(int n) {
            Graph = new List<WeightEdge>[n];
            rep(n, i => Graph[i] = new List<WeightEdge>());
        }
        public int Length => Graph.Length;
        public List<WeightEdge> this[int i] => Graph[i];
        public List<WeightEdge>[] Graph { get; }
        public void InputGraph(int m, in bool directed = true, in int offset = 1) {
            while (m-- > 0) {
                var (a, b, c) = next<int, int, long>();
                a -= offset;
                b -= offset;
                Graph[a].Add(new WeightEdge(b, c));
                if (!directed) Graph[b].Add(new WeightEdge(a, c));
            }
        }
        public void AddEdge(in int from, in int to, in long cost, in bool directed = true) {
            Graph[from].Add(new WeightEdge(to, cost));
            if (!directed) Graph[to].Add(new WeightEdge(from, cost));
        }
    }

    public readonly struct UnweightEdge : IEdge
    {
        public UnweightEdge(int to) => To = to;
        public int To { get; }
        public long Cost => 1;
    }

    public class UnweightGraph : Graph<UnweightEdge>
    {
        public UnweightGraph(int n) {
            Graph = new List<UnweightEdge>[n];
            rep(n, i => Graph[i] = new List<UnweightEdge>());
        }
        public int Length => Graph.Length;
        public List<UnweightEdge> this[int i] => Graph[i];
        public List<UnweightEdge>[] Graph { get; }
        public void InputGraph(int m, in bool directed = true, in int offset = 1) {
            while (m-- > 0) {
                var (a, b) = next<int, int>();
                a -= offset;
                b -= offset;
                Graph[a].Add(new UnweightEdge(b));
                if (!directed) Graph[b].Add(new UnweightEdge(a));
            }
        }
    }
    public class Dijkstra
    {
        public struct Node : IComparable<Node>
        {
            public Node(int num, int from, long cost) => (Number, From, Cost) = (num, from, cost);
            public readonly int Number;
            public int From { get; internal set; }
            public long Cost { get; internal set; }

            internal Node Copy() => new Node(Number, From, Cost);
            public static bool operator >(Node a, Node b) => a.Cost > b.Cost;
            public static bool operator <(Node a, Node b) => a.Cost < b.Cost;
            public int CompareTo(Node other) => Cost.CompareTo(other.Cost);
        }

        public const long INF = 1000000000000000100;
        private readonly int _n;
        public readonly Node[] Nodes;
        private readonly List<IEdge>[] _graph;

        public Dijkstra(int N) {
            Nodes = new Node[N];
            _graph = InitArray(N, _ => new List<IEdge>());
            for (int i = 0; i < N; i++) Nodes[i] = new Node(i, i, INF);
            _n = N;
        }

        public Dijkstra(WeightGraph graph) : this(graph.Length) {
            for (int i = 0; i < _n; i++) _graph[i].AddRange(graph[i].Cast<IEdge>());
        }
        public Dijkstra(UnweightGraph graph) : this(graph.Length) {
            for (int i = 0; i < _n; i++) _graph[i].AddRange(graph[i].Cast<IEdge>());
        }

        public void Add(int start, int end, long cost, bool undirected = false) {
            Validate(start, nameof(start));
            Validate(end, nameof(end));
            _graph[start].Add(new WeightEdge(end, cost));
            if (undirected) _graph[end].Add(new WeightEdge(start, cost));
        }

        /// <remarks>O((E+V) log V)</remarks>
        public Node[] Run(int start, long firstCost = 0) {
            Validate(start, nameof(start));
            var que = new PriorityQueue<Node>();
            var node = Nodes.Select(x => x.Copy()).ToArray();
            node[start].Cost = firstCost;

            foreach (var (to, cost) in _graph[start]) {
                node[to].Cost = cost + node[start].Cost;
                node[to].From = start;
                que.Push(node[to]);
            }

            while (que.Any()) {
                var next = que.Pop();
                if (next.Cost > node[next.Number].Cost) continue;
                foreach (var (to, cost) in _graph[next.Number].Where(e => node[e.To].Cost > next.Cost + e.Cost)) {
                    node[to].Cost = next.Cost + cost;
                    node[to].From = next.Number;
                    que.Push(node[to]);
                }
            }

            return node;
        }

        public static Node[] Restore(IReadOnlyList<Node> nodes, int to) {
            var node = nodes[to];
            var list = new List<Node> {node};
            while (node.Number != node.From) list.Add(node = nodes[node.From]);
            list.Reverse();
            return list.ToArray();
        }

        private void Validate(int val, string argument) {
            if (val.IsIn(.._n)) return;
            throw new ArgumentOutOfRangeException(argument);
        }
    }

    public static class Methods
    {
        [MethodImpl(256)] public static bool Assert(in bool b, in string message = null) =>
            b ? true : throw new Exception(message ?? "Assert failed.");
        [MethodImpl(256)] public static string JoinSpace<T>(this IEnumerable<T> source) => source.Join(" ");
        [MethodImpl(256)] public static string JoinEndline<T>(this IEnumerable<T> source) => source.Join("\n");
        [MethodImpl(256)] public static string Join<T>(this IEnumerable<T> source, string s) => string.Join(s, source);
        [MethodImpl(256)] public static string Join<T>(this IEnumerable<T> source, char c) =>
            string.Join(c.ToString(), source);
        public static int Gcd(int a, int b) => (int) Gcd((long) a, b);
        public static long Gcd(long a, long b) {
            while (true) {
                if (a < b) (a, b) = (b, a);
                if (a % b == 0) return b;
                var x = a;
                a = b;
                b = x % b;
            }
        }
        public static long Lcm(long a, long b) => a / Gcd(a, b) * b;
        public static bool IsPrime(long value) {
            if (value <= 1) return false;
            for (long i = 2; i * i <= value; ++i) if (value % i == 0) return false;
            return true;
        }
        public static long Pow(long a, int b) {
            long res = 1;
            while (b > 0) { if (b % 2 != 0) res *= a; a *= a; b >>= 1; }
            return res;
        }
        public static int PowMod(long a, long b, int p) => (int) PowMod(a, b, (long) p);
        public static long PowMod(long a, long b, long p) {
            long res = 1;
            while (b > 0) { if (b % 2 != 0) res = res * a % p; a = a * a % p; b >>= 1; }
            return res;
        }
        public static IEnumerable<long> Factors(long n) {
            Assert(n >= 0, "n must be greater than 0.");
            for (long i = 1; i * i <= n; ++i) {
                var div = DivRem(n, i, out var rem);
                if (rem > 0) continue;
                yield return div;
                if (i != div) yield return i;
            }
        }
        public static IEnumerable<int> Factors(int n) => Factors((long) n).Select(Convert.ToInt32);
        [MethodImpl(256)] public static int DivCeil(int a, int b) => (a + b - 1) / b;
        [MethodImpl(256)] public static long DivCeil(long a, long b) => (a + b - 1) / b;
        public static IEnumerable<T[]> Permutations<T>(IEnumerable<T> src) {
            var ret = new List<T[]>();
            Search(ret, new Stack<T>(), src.ToArray());
            return ret;

            static void Search(ICollection<T[]> perms, Stack<T> stack, T[] a) {
                int N = a.Length;
                if (N == 0) perms.Add(stack.Reverse().ToArray());
                else {
                    var b = new T[N - 1];
                    Array.Copy(a, 1, b, 0, N - 1);
                    for (int i = 0; i < a.Length; ++i) {
                        stack.Push(a[i]);
                        Search(perms, stack, b);
                        if (i < b.Length) b[i] = a[i];
                        stack.Pop();
                    }
                }
            }
        }
        public static long BinarySearch(long low, long high, Func<long, bool> expression) {
            while (low < high) {
                long middle = (high - low) / 2 + low;
                if (!expression(middle))
                    high = middle;
                else
                    low = middle + 1;
            }

            return high;
        }
        public static int LowerBound<T>(T[] arr, int start, int end, T value, IComparer<T> comparer) {
            int low = start;
            int high = end;
            while (low < high) {
                var mid = ((high - low) >> 1) + low;
                if (comparer.Compare(arr[mid], value) < 0)
                    low = mid + 1;
                else
                    high = mid;
            }

            return low;
        }
        public static int LowerBound<T>(T[] arr, T value) where T : IComparable =>
            LowerBound(arr, 0, arr.Length, value, Comparer<T>.Default);
        public static int UpperBound<T>(T[] arr, int start, int end, T value, IComparer<T> comparer) {
            var (low, high) = (start, end);
            while (low < high) {
                var mid = ((high - low) >> 1) + low;
                if (comparer.Compare(arr[mid], value) <= 0) low = mid + 1;
                else high = mid;
            }

            return low;
        }
        public static int UpperBound<T>(T[] arr, T value) => 
            UpperBound(arr, 0, arr.Length, value, Comparer<T>.Default);
        [MethodImpl(256)]
        public static IEnumerable<TResult> Repeat<TResult>(TResult value, int count) => Enumerable.Repeat(value, count);
        [MethodImpl(256)] public static string AsString(this IEnumerable<char> source) => new string(source.ToArray());
        public static IEnumerable<long> CumSum(this IEnumerable<long> source) {
            long sum = 0; foreach (var item in source) yield return sum += item;
        }
        public static IEnumerable<int> CumSum(this IEnumerable<int> source) {
            int sum = 0; foreach (var item in source) yield return sum += item;
        }
        [MethodImpl(256)] public static bool IsIn<T>(this T value, T l, T r) where T : IComparable<T> =>
            l.CompareTo(r) > 0 ? throw new ArgumentException() : l.CompareTo(value) <= 0 && value.CompareTo(r) < 0;
        [MethodImpl(256)] public static bool IsIn(this in int value, in Range range) =>
            value.IsIn(range.Start.Value, range.End.Value);
        [MethodImpl(256)] public static bool IsIn(this in Index value, in Range range) =>
            value.IsFromEnd && value.Value.IsIn(range.Start.Value, range.End.Value);
        public static IEnumerable<int> Range(int start, int end, int step = 1) {
            for (var i = start; i < end; i += step) yield return i;
        }
        public static IEnumerable<int> Range(int end) => Range(0, end);
        public static IEnumerable<int> Range(Range range, int step = 1) =>
            Range(range.Start.Value, range.End.Value, step);
        [MethodImpl(256)] public static T[] Sort<T>(this T[] arr) where T : IComparable<T> {
            var array = arr[..]; Array.Sort(array); return array;
        }
        [MethodImpl(256)]
        public static T[] Sort<T, U>(this T[] arr, Func<T, U> selector) where U : IComparable<U> {
            var array = arr[..];
            Array.Sort(array, (a, b) => selector(a).CompareTo(selector(b)));
            return array;
        }
        [MethodImpl(256)] public static T[] SortDescending<T>(this T[] arr) where T : IComparable<T> {
            var array = arr[..];
            Array.Sort(array, (a, b) => b.CompareTo(a));
            return array;
        }
        [MethodImpl(256)]
        public static T[] SortDescending<T, U>(this T[] arr, Func<T, U> selector) where U : IComparable<U> {
            var array = arr[..];
            Array.Sort(array, (a, b) => selector(b).CompareTo(selector(a)));
            return array;
        }
        public static T[] Unique<T>(this IEnumerable<T> arr) {
            var source = arr.ToArray();
            var ret = new List<T>(source.Length);
            var set = new SortedSet<T>();
            ret.AddRange(source.Where(val => set.Add(val)));

            return ret.ToArray();
        }
        [MethodImpl(256)] public static bool chmin<T>(ref T a, T b)
            where T : IComparable<T> {
            if (a.CompareTo(b) > 0) { a = b; return true; }
            return false;
        } 
        [MethodImpl(256)] public static bool chmax<T>(ref T a, T b)
            where T : IComparable<T> {
            if (a.CompareTo(b) < 0) { a = b; return true; }
            return false;
        }
        public static T[] InitArray<T>(int n, Func<int, T> init) {
            var res = new T[n];
            for (int i = 0; i < n; i++) res[i] = init(i);
            return res;
        }
        public static T[][] JaggedArray2D<T>(int a, int b, T defaultValue = default) {
            var ret = new T[a][];
            for (int i = 0; i < a; ++i) ret[i] = Enumerable.Repeat(defaultValue, b).ToArray();
            return ret;
        }
        public static T[,] Array2D<T>(int a, int b, T defaultValue = default) {
            var ret = new T[a, b];
            for (int i = 0; i < a; ++i) for (int j = 0; j < b; ++j) ret[i, j] = defaultValue;
            return ret;
        }
        public static T[,] To2DArray<T>(this T[][] array) {
            if (!array.Any()) return new T[0, 0];

            int len = array[0].Length;
            if (array.Any(x => x.Length != len))
                throw new ArgumentException("Length of each array must be same.", nameof(array));

            var ret = new T[array.Length, len];
            for (int i = 0; i < array.Length; ++i) for (int j = 0; j < len; ++j) ret[i, j] = array[i][j];
            return ret;
        }
        [MethodImpl(256)] public static T Min<T>(params T[] col) => col.Min();
        [MethodImpl(256)] public static T Max<T>(params T[] col) => col.Max();
        [MethodImpl(256)] public static IEnumerable<(T, int)> WithIndex<T>(this IEnumerable<T> source) =>
            source.Select((x, i) => (x, i));
        [MethodImpl(256)] public static (T, U, V)[] Zip<T, U, V>(
            IReadOnlyCollection<T> t,
            IReadOnlyCollection<U> u,
            IReadOnlyCollection<V> v
        ) {
            Assert(t.Count == u.Count && u.Count == v.Count);
            return t.Zip(u, (a, b) => (a, b))
                .Zip(v, (tuple, c) => (tuple.Item1, tuple.Item2, c)).ToArray();
        }
        [MethodImpl(256)] public static void rep(in int start, in int end, Action<int> func) {
            for (int i = start; i < end; ++i) func(i);
        }
        [MethodImpl(256)] public static void rep(in int end, Action<int> func) => rep(0, end, func);
        [MethodImpl(256)] public static void rep1(in int end, Action<int> func) => rep(1, end + 1, func);
        [MethodImpl(256)] public static void repr(in int end, Action<int> func) {
            for (int i = end - 1; i >= 0; --i) func(i);
        }
        [MethodImpl(256)]
        public static void each<T>(this IEnumerable<T> source, Action<T> func) {
            foreach (var item in source) func(item);
        }
        [MethodImpl(256)]
        public static void eachWithIndex<T>(this IEnumerable<T> source, Action<T, int> func) {
            int index = 0; foreach (var item in source) func(item, index++);
        }
        [MethodImpl(256)] public static int bit(in int x) => 1 << x;
        [MethodImpl(256)] public static long bitl(in int x) => 1L << x;
    }
    public class UnorderedMap<T, U> : Dictionary<T, U>
    {
        public new U this[T k] {
            get =>
                TryGetValue(k, out var v) ? v : base[k] = default;
            set =>
                base[k] = value;
        }
    }
    public class Map<T, U> : SortedDictionary<T, U>
    {
        readonly U _default;
        public Map(U defaultValue = default) {
            _default = defaultValue;
        }
        public new U this[T k] {
            get =>
                TryGetValue(k, out var v) ? v : base[k] = _default;
            set =>
                base[k] = value;
        }
    }
    public class Scanner<T>
    {
        public T r => next<T>();
        public T next() => r;

        IEnumerable<T> enumerable(int N) { for (int i = 0; i < N; ++i) yield return r; }

        public T[] array(in int N) => enumerable(N).ToArray();
        public List<T> list(in int N) => enumerable(N).ToList();
        public T[,] array2d(in int N, in int M) => next2DArray<T>(N, M);
        public T[][] listArray(in int n) {
            var ret = new T[n][];
            for (int i = 0; i < n; i++) ret[i] = array(next<int>());
            return ret;
        }

        public void Deconstruct(out T _1, out T _2) => (_1, _2) = (r, r);
        public void Deconstruct(out T _1, out T _2, out T _3) => (_1, _2, _3) = (r, r, r);
        public void Deconstruct(out T _1, out T _2, out T _3, out T _4) =>
            (_1, _2, _3, _4) = (r, r, r, r);
        public void Deconstruct(out T _1, out T _2, out T _3, out T _4, out T _5) =>
            (_1, _2, _3, _4, _5) = (r, r, r, r, r);
        public void Deconstruct(out T _1, out T _2, out T _3, out T _4, out T _5, out T _6) =>
            (_1, _2, _3, _4, _5, _6) = (r, r, r, r, r, r);
        public void Deconstruct(out T _1, out T _2, out T _3, out T _4, out T _5, out T _6, out T _7) =>
            (_1, _2, _3, _4, _5, _6, _7) = (r, r, r, r, r, r, r);
        public void Deconstruct(out T _1, out T _2, out T _3, out T _4, out T _5, out T _6, out T _7, out T _8) =>
            (_1, _2, _3, _4, _5, _6, _7, _8) = (r, r, r, r, r, r, r, r);
        public void Deconstruct(out T _1, out T _2, out T _3, out T _4, 
            out T _5, out T _6, out T _7, out T _8, out T _9) =>
            (_1, _2, _3, _4, _5, _6, _7, _8, _9) = (r, r, r, r, r, r, r, r, r);
        public void Deconstruct(out T _1, out T _2, out T _3, out T _4,
            out T _5, out T _6, out T _7, out T _8, out T _9, out T _10) =>
            (_1, _2, _3, _4, _5, _6, _7, _8, _9, _10) = (r, r, r, r, r, r, r, r, r, r);
        
        public static implicit operator T(Scanner<T> sc) => sc.r;
    }
    public static class Input
    {
        const char _separator = ' ';
        static readonly Queue<string> _input = new Queue<string>();
        static readonly StreamReader sr =
#if FILE
            new StreamReader("in.txt");
#else
            new StreamReader(Console.OpenStandardInput());
#endif

        public static string ReadLine => sr.ReadLine();
        static string ReadStr => Read;
        static int ReadInt => int.Parse(Read);
        static long ReadLong => long.Parse(Read);
        static ulong ReadULong => ulong.Parse(Read);
        static double ReadDouble => double.Parse(Read);
        static BigInteger ReadBigInteger => BigInteger.Parse(Read);

        public static string Read {
            get {
                if (_input.Any()) return _input.Dequeue();
                foreach (var val in sr.ReadLine().Split(_separator)) _input.Enqueue(val);
                return _input.Dequeue();
            }
        }

        public static string next() => Read;
        public static T next<T>() =>
            default(T) switch {
                sbyte _ => (T) (object) (sbyte) ReadInt,
                short _ => (T) (object) (short) ReadInt,
                int _ => (T) (object) ReadInt,
                long _ => (T) (object) ReadLong,
                byte _ => (T) (object) (byte) ReadULong,
                ushort _ => (T) (object) (ushort) ReadULong,
                uint _ => (T) (object) (uint) ReadULong,
                ulong _ => (T) (object) ReadULong,
                float _ => (T) (object) (float) ReadDouble,
                double _ => (T) (object) ReadDouble,
                string _ => (T) (object) ReadStr,
                char _ => (T) (object) ReadStr[0],
                BigInteger _ => (T) (object) ReadBigInteger,
                _ => typeof(T) == typeof(string)
                    ? (T) (object) ReadStr
                    : throw new NotSupportedException(),
            };
        public static (T, U) next<T, U>() => (next<T>(), next<U>());
        public static (T, U, V) next<T, U, V>() => (next<T>(), next<U>(), next<V>());
        public static (T, U, V, W) next<T, U, V, W>() => (next<T>(), next<U>(), next<V>(), next<W>());
        public static (T, U, V, W, X) next<T, U, V, W, X>() => (next<T>(), next<U>(), next<V>(), next<W>(), next<X>());
        public static T[] nextArray<T>(in int size) {
            var ret = new T[size]; for (int i = 0; i < size; ++i) ret[i] = next<T>(); return ret;
        }
        public static T[,] next2DArray<T>(int n, in int m) {
            var ret = new T[n, m];
            for (int i = 0; i < n; ++i) for (int j = 0; j < n; ++j) ret[i, j] = next<T>(); return ret;
        }
        public static (T[], U[]) nextArray<T, U>(in int size) {
            var ret1 = new T[size]; var ret2 = new U[size];
            for (int i = 0; i < size; ++i) (ret1[i], ret2[i]) = next<T, U>();
            return (ret1, ret2);
        }
        public static (T[], U[], V[]) nextArray<T, U, V>(in int size) {
            var ret1 = new T[size]; var ret2 = new U[size]; var ret3 = new V[size];
            for (int i = 0; i < size; ++i) (ret1[i], ret2[i], ret3[i]) = next<T, U, V>();
            return (ret1, ret2, ret3);
        }
    }
    public static class Output
    {
        [MethodImpl(256)] public static void print() => Console.WriteLine();
        [MethodImpl(256)] public static void print(in string s, bool endline = true) {
            if (endline) Console.WriteLine(s); else Console.Write(s);
        }
        [MethodImpl(256)] public static void print(in char s, bool endline = true) {
            if (endline) Console.WriteLine(s); else Console.Write(s);
        }
        [MethodImpl(256)] public static void print(in int v, bool endline = true) {
            if (endline) Console.WriteLine(v); else Console.Write(v);
        }
        [MethodImpl(256)] public static void print(in long v, bool endline = true) {
            if (endline) Console.WriteLine(v); else Console.Write(v);
        }
        [MethodImpl(256)] public static void print(in ulong v, bool endline = true) {
            if (endline) Console.WriteLine(v); else Console.Write(v);
        }
        [MethodImpl(256)] public static void print(in bool b) => PrintBool(b);
        [MethodImpl(256)] public static void print(in object v) => Console.WriteLine(v);
        [MethodImpl(256)] public static void print<T>(in IEnumerable<T> array, string separator = " ") =>
            Console.WriteLine(array.Join(separator));
        [MethodImpl(256)] public static void prints<T>(params T[] t) => print(t);
        
#if LOCAL
        [MethodImpl(256)] public static void debug<T>(in T value, bool endline = true) {
            if (endline) Console.WriteLine(value);else Console.Write(value);
        }
#else
        public static void debug(params object[] obj) { }
#endif

        [MethodImpl(256)] static void PrintBool(in bool val, in string yes = null, in string no = null) =>
            print(val ? yes ?? _yes : no ?? _no);
        static string _yes = "Yes", _no = "No";

        public static void SetYesNoString(in YesNoType t) => (_yes, _no) = YesNoString[t];
        public static void SetYesNoString(in string yes, in string no) => (_yes, _no) = (yes, no);

        static readonly Dictionary<YesNoType, (string yes, string no)>
            YesNoString = new Dictionary<YesNoType, (string, string)> {
                    {YesNoType.Yes_No, ("Yes", "No")},
                    {YesNoType.YES_NO, ("YES", "NO")},
                    {YesNoType.Upper, ("YES", "NO")},
                    {YesNoType.yes_no, ("yes", "no")},
                    {YesNoType.Lower, ("yes", "no")},
                    {YesNoType.Possible_Impossible, ("Possible", "Impossible")},
                    {YesNoType.Yay, ("Yay!", ":(")},
                };

        public static readonly (string yes, string no) YN_Possible = ("Possible", "Impossible"),
            YN_lower = ("yes", "no"), YN_upper = ("YES", "NO"), YN_Yay = ("Yay!", ":(");

        public static void Yes() => print(_yes);
        public static void No() => print(_no);

        public static object cout { set => Console.WriteLine(value); }
#if LOCAL
        public static object dout { set => Console.WriteLine(value); }
#else
        public static object dout { set { } }
#endif
        public static object cerr { set => Console.Error.WriteLine(value); }

        public const string endl = "\n";

        public enum YesNoType { Yes_No, YES_NO, Upper, yes_no, Lower, Possible_Impossible, Yay }
    }
    public class Program
    {
        public static void Main(string[] args) {
            var sw = new StreamWriter(Console.OpenStandardOutput()) {AutoFlush = false};
            Console.SetOut(sw);
            new Solver().Main();
            Console.Out.Flush();
        }
    }
    partial class Solver
    {
        readonly Scanner<int> Int;
        readonly Scanner<long> Long;
        readonly Scanner<string> String;
        public Solver() => (Int, String, Long) = (new Scanner<int>(), new Scanner<string>(), new Scanner<long>());
        const int INF = 1000000010;
        const long LINF = 1000000000000000100;
        const double EPS = 1e-9;
        public static readonly int[] dx = {-1, 0, 0, 1}, dy = {0, 1, -1, 0};
    }
}