Problem: Problem

The penguins Fluoro is in an infinitely wide ice cube ($ sx $, $ sy $).
There is a hole in the trout ($ tx $, $ ty $) through which water can enter.
There are $ n $ lumps of ice on the ice, each in the square ($ x_i $, $ y_i $).


Fluoro can move up, down, left and right in four directions.
It's slippery on the ice, so when you move it keeps moving until it hits a block of ice.
When it hits a lump of ice, it stops just before the square with the lump of ice.
You can enter the hole by passing through the square of the hole.


Fluoro can stop in the middle by stepping on it only once.

It hurts when it hits a lump of ice, so I want to reduce the number of hits as much as possible.
Find the minimum number of hits before moving to a square with a hole ($ tx $, $ ty $).
If you can't reach it, print $-$ 1.

Constraints

The input satisfies the following conditions.

* $ 0 \ leq n \ leq 10 ^ 5 $
* $ 0 \ leq sx $, $ sy $, $ tx $, $ ty $, $ x_i $, $ y_i \ leq 10 ^ 9 $
* All given coordinates are different

Input

The input is given in the following format.


$ sx $ $ sy $
$ tx $ $ ty $
$ n $
$ x_1 $ $ y_1 $
...
$ x_n $ $ y_n $


All inputs are given as integers.
The coordinates of the cell where Fluoro is on the first line are given separated by blanks.
The coordinates of the cells with holes in the second line are given separated by blanks.
The third line gives the number of ice cubes $ n $.
The coordinates of the square with the ice block on the following $ n $ line are given, separated by blanks.

Output

Output the minimum number of hits before moving to a hole.
If you can't reach it, print $-$ 1.

Examples

Input

0 0
13 33
2
0 34
14 0


Output

0


Input

0 1
5 0
4
2 1
1 3
4 2
3 0


Output

4


Input

0 0
0 2
1
0 1


Output

-1

Solution (in CPP):

Solution:
#ifndef VS
#include<bits/stdc++.h>
#endif

using namespace std;
typedef long long LL;

#ifdef BTK
#define DEBUG if(1)
#else
#define CIN_ONLY if(1)
struct cww {cww() {CIN_ONLY{ios::sync_with_stdio(false); cin.tie(0);}}
}star;
#define DEBUG if(0)
#endif

#define ALL(v) (v).begin(),(v).end()
#define REC(ret, ...) std::function<ret (__VA_ARGS__)>
template <typename T>inline bool chmin(T &l, T r){bool a = l>r; if (a)l = r; return a;}
template <typename T>inline bool chmax(T &l, T r){bool a = l<r; if (a)l = r; return a;}
template <typename T>istream& operator>>(istream &is, vector<T> &v){for (auto &it : v)is >> it;return is;}

class range {private: struct I { int x; int operator*() { return x; }bool operator!=(I& lhs) { return x<lhs.x; }void operator++() { ++x; } }; I i, n;public:range(int n) :i({ 0 }), n({ n }) {}range(int i, int n) :i({ i }), n({ n }) {}I& begin() { return i; }I& end() { return n; }};

constexpr int MAX_N = 812345;
struct P{
	int r, c;
};
istream& operator>>(istream &is, P &v) { is >> v.r >> v.c; return is; }

P S, T;
int N;
P in[MAX_N];
namespace Z{
	int latte[MAX_N];
	int id;
	void init() {
		id = 0;
	}
	inline void set(int v) {
		latte[id++] = v;
	}
	inline void build() {
		sort(latte, latte + id);
		id = unique(latte, latte + id) - latte;
	}
	inline int ItoZ(int v) {
		return lower_bound(latte, latte + id, v) - latte;
	}
	inline int ZtoI(int v) {
		return latte[v];
	}
}

bool input() {
	if(cin >> S >> T);
	else return false;
	cin >> N;
	Z::init();
	for (int j : {-1, 0, 1}) {
		Z::set(S.r + j);
		Z::set(S.c + j);
		Z::set(T.r + j);
		Z::set(T.c + j);
	}
	for (int i : range(N)) {
		cin >> in[i];
		for (int j : {-1, 0, 1}) {
			Z::set(in[i].r + j);
			Z::set(in[i].c + j);
		}
	}
	Z::build();
	S.r = Z::ItoZ(S.r);	S.c = Z::ItoZ(S.c);
	T.r = Z::ItoZ(T.r);	T.c = Z::ItoZ(T.c);
	for (int i : range(N)) {
		in[i].r = Z::ItoZ(in[i].r);
		in[i].c = Z::ItoZ(in[i].c);
	}
#ifdef BTK
	cout << S.r << " " << S.c << endl;
	cout << T.r << " " << T.c << endl;
	cout << N << endl;
	for (int i : range(N)) {
		cout << in[i].r << " " << in[i].c << endl;
	}
#endif
	return true;
}
typedef vector<int> V;
typedef vector<V> VV;
typedef vector<VV> VVV;
constexpr int dr[4] = { 1,0,0,-1 };
constexpr int dc[4] = { 0,1,-1,0 };
const string ds = { "DRLU" };
struct Tate {
	static constexpr int index = 0;
	static inline bool comp(const int lr, const int lc, const int rr, const int rc) {
		return lr == rr ? lc < rc : lr < rr;
	}
};
struct Yoko {
	static constexpr int index = 1;
	static inline bool comp(const int lr, const int lc, const int rr, const int rc) {
		return lc == rc ? lr < rr : lc < rc;
	}
};

namespace pts {
	int pt[2][MAX_N];
	int cr[MAX_N];
	template<typename dir>
	inline bool ice_comp(const int li, const int ri) {
		return dir::comp(in[li].r, in[li].c, in[ri].r, in[ri].c);
	}
	void build() {
		iota(pt[Yoko::index], pt[Yoko::index] + N, 0);
		iota(pt[Tate::index], pt[Tate::index] + N, 0);
		sort(pt[Yoko::index], pt[Yoko::index] + N, ice_comp<Yoko>);
		sort(pt[Tate::index], pt[Tate::index] + N, ice_comp<Tate>);
	}
	template<typename dir>
	inline int lower_bound(int r, int c) {
		int lb = -1, ub = N;
		while (ub - lb > 1) {
			const int mid = (lb + ub) / 2;
			(!dir::comp(r, c, in[pt[dir::index][mid]].r, in[pt[dir::index][mid]].c) ? lb : ub) = mid;
		}
		return ub;
	}
	inline bool isIce(int r, int c) {

		int id = lower_bound<Yoko>(r, c);
		return id != N && in[pt[Yoko::index][id]].r == r && in[pt[Yoko::index][id]].c == c;
	}
}

struct Down {
	static constexpr int index = 0;
	static inline int getIce(int r, int c) {
		int id = pts::lower_bound<Yoko>(r, c);
		if (id != N && in[pts::pt[Yoko::index][id]].c == c)
			return pts::pt[Yoko::index][id];
		else return -1;
	}
};

struct Right {
	static constexpr int index = 1;
	static inline int getIce(int r, int c) {
		int id = pts::lower_bound<Tate>(r, c);
		if (id != N && in[pts::pt[Tate::index][id]].r == r)
			return pts::pt[Tate::index][id];
		else return -1;
	}
};
struct Left {
	static constexpr int index = 2;
	static inline int getIce(int r, int c) {
		int id = pts::lower_bound<Tate>(r, c) - 1;
		if (id != -1 && in[pts::pt[Tate::index][id]].r == r)
			return pts::pt[Tate::index][id];
		else return -1;
	}
};
struct Up {
	static constexpr int index = 3;
	static inline int getIce(int r, int c) {
		int id = pts::lower_bound<Yoko>(r, c) - 1;
		if (id != -1 && in[pts::pt[Yoko::index][id]].c == c)
			return pts::pt[Yoko::index][id];
		else return -1;
	}
};
		
inline bool isReachable(int r,int c,int nr,int nc) {
	if (r == nr) {
		if (c < nc) {
			const int id = Right::getIce(r, c);
			return id == -1 || nc < in[id].c;
		}
		else if (nc < c) {
			const int id = Left::getIce(r, c);
			return id == -1 || in[id].c < nc;
		}
		else return true;
	}
	else if (c == nc) {
		if (r < nr) {
			const int id = Down::getIce(r, c);
			return id == -1 || nr < in[id].r;
		}
		else if (nr < r) {
			const int id = Up::getIce(r, c);
			return id == -1 || in[id].r < nr;
		}
		else return true;
	}
	else return false;
}


vector<P> g[MAX_N][4];
vector<P> rg[MAX_N][4];

int dist[MAX_N][4];
int rdist[MAX_N][4];
template<typename dir> 
inline void addArc(const int i, const int j, const int r,const int c) {
	const int id = dir::getIce(r, c);
	if (id != -1) {
		g[i][j].push_back(P{ id,3 - dir::index });
		rg[id][3 - dir::index].push_back(P{ i,j });
	}
}
void buildGraph(){
	for (int i : range(N)) {
		for (int d : range(4)) {
			int r = in[i].r + dr[d];
			int c = in[i].c + dc[d];
			if (pts::isIce(r, c))continue;
			addArc<Down>(i, d, r, c);
			addArc<Up>(i, d, r, c);
			addArc<Left>(i, d, r, c);
			addArc<Right>(i, d, r, c);
		}
	}
}
template<typename dir>
void uku(){
	int id = dir::getIce(S.r, S.c);
	if (id != -1) {
		const int r = in[id].r + dr[3 - dir::index];
		const int c = in[id].c + dc[3 - dir::index];
		dist[id][3 - dir::index] = (S.r != r || S.c != c);
	}
}

constexpr int INF = 1e7;
queue<P> que;
void bfs() {
	uku<Down>();
	uku<Left>();
	uku<Right>();
	uku<Up>();
	for (int i : range(N)) {
		for (int d : range(4)) {
			if (dist[i][d] == 0)que.push(P{ i,d });
		}
	}
	for (int i : range(N)) {
		for (int d : range(4)) {
			if (dist[i][d] == 1)que.push(P{ i,d });
		}
	}
	while (!que.empty()) {
		int i = que.front().r;
		int j = que.front().c;
		que.pop();
		for (auto &it : g[i][j]) {
			int ni = it.r;
			int nj = it.c;
			if (chmin(dist[ni][nj], dist[i][j] + 1)) {
				que.push(it);
			}
		}
	}
	for (int i : range(N)) {
		for (int d : range(4)) {
			const int r = in[i].r + dr[d];
			const int c = in[i].c + dc[d];
			if (isReachable(r, c, T.r, T.c)) {
				rdist[i][d] = 0;
				que.push(P{ i,d });
			}
		}
	}
	while (!que.empty()) {
		int i = que.front().r;
		int j = que.front().c;
		que.pop();
		for (auto &it : rg[i][j]) {
			int ni = it.r;
			int nj = it.c;
			if (chmin(rdist[ni][nj], rdist[i][j] + 1)) {
				que.push(it);
			}
		}
	}
}

template<typename SEG> using SetInitialLeaf = function<void(SEG&, int)>;
template<typename SEG> using SetInitialSegment = function<void(SEG&, const int, const int)>;
template<typename RET, typename SEG> using GetSingleSegment = function<RET(SEG&, const int, const int)>;
template<typename RET> using GetMergedSegment = function<RET(RET, RET)>;
template<typename SEG, typename Q> using UpdateSingleSegment = function<void(SEG&, Q)>;

struct node { int ret; };

SetInitialLeaf<node>
set_leaf = [](node &v, const int id) {
	v.ret = INF;
};

SetInitialSegment<node>
set_segment = [](node &v, const int l, const int r) {};

GetSingleSegment<int, node>
segment_min = [](node &v, const int l, const int r) {
	return v.ret;
};

GetMergedSegment<int>
merge_segment = [](int l, int r) {
	return l < r ? l : r;
};

UpdateSingleSegment<node, int>
force_update = [](node &v, int l) {
	v.ret = l;
};

UpdateSingleSegment<node, int>
weak_update = [](node &v, int l) {
	if (v.ret > l)v.ret = l;
};

template<typename T>
struct BufferManager {
	T *mem;
	int ptr;
	BufferManager(T* mem) {
		ptr = 0;
		this->mem = mem;
	}
	T* get(int m) {
		ptr += m;
		return mem + ptr - m;
	}
	void reset() {
		ptr = 0;
	}
};

namespace NodeBuffer {
	constexpr int BufferSize = 812345;
	using NodeType = node;
	NodeType mem[BufferSize];
	BufferManager<NodeType> buffer(mem);
}

template<typename Node, typename RET>
struct SegmentTree {
	int size;
	Node *seg;
	GetSingleSegment<RET, Node> get_single_segment;
	GetMergedSegment<RET> get_merged_segment;
	void init(int l, int r, SetInitialSegment<Node>& init_segment, SetInitialLeaf<Node>& init_leaf, int k = 0) {
		auto &v = seg[k];
		init_segment(v, l, r);
		if (r - l == 1) {
			//葉の時の処理
			init_leaf(v, l);
		}
		else if (r - l>1) {
			int m = (l + r) / 2;
			init(l, m, init_segment, init_leaf, k * 2 + 1);
			init(m, r, init_segment, init_leaf, k * 2 + 2);
			v.ret = get_merged_segment(
				get_single_segment(seg[k * 2 + 1], l, m),
				get_single_segment(seg[k * 2 + 2], m, r)
			);
		}
	}
	SegmentTree(
		int n,
		GetSingleSegment<RET, Node> gss,
		GetMergedSegment<RET> gms,
		SetInitialSegment<Node> sis,
		SetInitialLeaf<Node> sil,
		BufferManager<Node> buf = NodeBuffer::buffer
	)
		:get_single_segment(gss),
		get_merged_segment(gms) {
		size = 1; while (size<n)size *= 2;
		seg = buf.get(size + 10);
		init(0, size, sis, sil);
	}
#define LQ a,b,k*2+1,l,m
#define RQ a,b,k*2+2,m,r
	RET get(int a, int b, int k, int l, int r) {
		if (a <= l && r <= b)return get_single_segment(seg[k], l, r);
		int m = (l + r) / 2;
		bool ll = !(m <= a || b <= l);
		bool rr = !(r <= a || b <= m);
		RET ret;
		if (ll&&rr)ret = get_merged_segment(get(LQ), get(RQ));
		else if (ll)ret = get(LQ); else ret = get(RQ);
		return ret;
	}
	RET get(int a, int b) {
		return get(a, b, 0, 0, size);
	}
	template<typename Q>
	void update(int a, int b, int k, int l, int r, UpdateSingleSegment<Node, Q> &update_segment, Q value) {
		if (r <= a || b <= l)return;
		if (a <= l && r <= b) {
			update_segment(seg[k], value);
		}
		else {
			int m = (l + r) / 2;
			update(LQ, update_segment, value);
			update(RQ, update_segment, value);
			seg[k].ret = get_merged_segment(
				get_single_segment(seg[k * 2 + 1], l, m),
				get_single_segment(seg[k * 2 + 2], m, r)
			);
		}
	}
	template<typename Q>
	void update_segment(int a, int b, UpdateSingleSegment<Node, Q> &update_segment, Q value) {
		update(a, b, 0, 0, size, update_segment, value);
	}

	template<typename Q>
	void update_element(int a, UpdateSingleSegment<Node, Q> &update_segment, Q value) {
		update(a, a + 1, 0, 0, size, update_segment, value);
	}
};

int ret = INF;
void solve_down() {
	constexpr int dir = Down::index;
	constexpr int s = Left::index;
	SegmentTree<node, int> rmq(Z::id, segment_min, merge_segment, set_segment, set_leaf);
	auto query = [&](int l, int r) {
		if (r - l >= 1)return rmq.get(l, r);
		else return INF;
	};
	for (int lb = 0; lb < N;) {
		int ub = lb;
		int* pt = pts::pt[Tate::index];
		while (ub < N&&
			in[pt[lb]].r == in[pt[ub]].r) {
			ub++;
		}
		chmin(ret, rdist[pt[lb]][s] + query(0, in[pt[lb]].c) + 1);
		for (int i : range(lb, ub-1)) {
			const int seg_cost = query(in[pt[i]].c + 1, in[pt[i + 1]].c);
			chmin(ret, rdist[pt[i]][3 - s] + seg_cost + 1);
			chmin(ret, rdist[pt[i + 1]][s] + seg_cost + 1);
		}
		chmin(ret, rdist[pt[ub - 1]][3 - s] + query(in[pt[ub - 1]].c + 1, Z::id) + 1);
		for (int i : range(lb, ub)) {
			rmq.update_element(in[pt[i]].c, force_update, dist[pt[i]][dir]);
			rmq.update_element(in[pt[i]].c + dc[s], weak_update, dist[pt[i]][s]);
			rmq.update_element(in[pt[i]].c + dc[3 - s], weak_update, dist[pt[i]][3 - s]);
		}
		lb = ub;
	}
	NodeBuffer::buffer.reset();
}

void solve_right() {
	constexpr int dir = Right::index;
	constexpr int s = Up::index;
	SegmentTree<node, int> rmq(Z::id, segment_min, merge_segment, set_segment, set_leaf);
	auto query = [&](int l, int r) {
		if (r - l >= 1)return rmq.get(l, r);
		else return INF;
	};
	for (int lb = 0; lb < N;) {
		int ub = lb;
		int* pt = pts::pt[Yoko::index];
		while (ub < N&&
			in[pt[lb]].c == in[pt[ub]].c) {
			ub++;
		}
		chmin(ret, rdist[pt[lb]][s] + query(0, in[pt[lb]].r) + 1);
		for (int i : range(lb, ub - 1)) {
			const int seg_cost = query(in[pt[i]].r + 1, in[pt[i + 1]].r);
			chmin(ret, rdist[pt[i]][3 - s] + seg_cost + 1);
			chmin(ret, rdist[pt[i + 1]][s] + seg_cost + 1);
		}
		chmin(ret, rdist[pt[ub - 1]][3 - s] + query(in[pt[ub - 1]].r + 1, Z::id) + 1);
		for (int i : range(lb, ub)) {
			rmq.update_element(in[pt[i]].r, force_update, dist[pt[i]][dir]);
			rmq.update_element(in[pt[i]].r + dr[s], weak_update, dist[pt[i]][s]);
			rmq.update_element(in[pt[i]].r + dr[3 - s], weak_update, dist[pt[i]][3 - s]);
		}
		lb = ub;
	}
	NodeBuffer::buffer.reset();
}

void solve_up() {
	constexpr int dir = Up::index;
	constexpr int s = Left::index;
	SegmentTree<node, int> rmq(Z::id, segment_min, merge_segment, set_segment, set_leaf);
	auto query = [&](int l, int r) {
		if (r - l >= 1)return rmq.get(l, r);
		else return INF;
	};
	for (int lb = N-1; lb >= 0;) {
		int ub = lb;
		int* pt = pts::pt[Tate::index];
		while (ub >=0 &&
			in[pt[lb]].r == in[pt[ub]].r) {
			ub--;
		}
		chmin(ret, rdist[pt[ub+1]][s] + query(0, in[pt[ub+1]].c) + 1);
		for (int i : range(ub+1, lb)) {
			const int seg_cost = query(in[pt[i]].c + 1, in[pt[i + 1]].c);
			chmin(ret, rdist[pt[i]][3 - s] + seg_cost + 1);
			chmin(ret, rdist[pt[i + 1]][s] + seg_cost + 1);
		}
		chmin(ret, rdist[pt[lb]][3 - s] + query(in[pt[lb]].c + 1, Z::id) + 1);
		for (int i : range(ub+1, lb+1)) {
			rmq.update_element(in[pt[i]].c, force_update, dist[pt[i]][dir]);
			rmq.update_element(in[pt[i]].c + dc[s], weak_update, dist[pt[i]][s]);
			rmq.update_element(in[pt[i]].c + dc[3 - s], weak_update, dist[pt[i]][3 - s]);
		}
		lb = ub;
	}
	NodeBuffer::buffer.reset();
}

void solve_left() {
	constexpr int dir = Left::index;
	constexpr int s = Up::index;
	SegmentTree<node, int> rmq(Z::id, segment_min, merge_segment, set_segment, set_leaf);
	auto query = [&](int l, int r) {
		if (r - l >= 1)return rmq.get(l, r);
		else return INF;
	};
	for (int lb = N-1; lb >= 0;) {
		int ub = lb;
		int* pt = pts::pt[Yoko::index];
		while (ub >=0&&
			in[pt[lb]].c == in[pt[ub]].c) {
			ub--;
		}
		chmin(ret, rdist[pt[ub+1]][s] + query(0, in[pt[ub+1]].r) + 1);
		for (int i : range(ub+1, lb)) {
			const int seg_cost = query(in[pt[i]].r + 1, in[pt[i + 1]].r);
			chmin(ret, rdist[pt[i]][3 - s] + seg_cost + 1);
			chmin(ret, rdist[pt[i + 1]][s] + seg_cost + 1);
		}
		chmin(ret, rdist[pt[lb]][3 - s] + query(in[pt[lb]].r + 1, Z::id) + 1);
		for (int i : range(ub+1, lb+1)) {
			rmq.update_element(in[pt[i]].r, force_update, dist[pt[i]][dir]);
			rmq.update_element(in[pt[i]].r + dr[s], weak_update, dist[pt[i]][s]);
			rmq.update_element(in[pt[i]].r + dr[3 - s], weak_update, dist[pt[i]][3 - s]);
		}
		lb = ub;
	}
	NodeBuffer::buffer.reset();
}
inline bool isReachableWithHop(int r,int c) {
	return (isReachable(r, c, r, T.c) &&
		isReachable(r, T.c, T.r, T.c)) ||
		(isReachable(r, c, T.r, c) &&
			isReachable(T.r, c, T.r, T.c));
}

int main() {
	while (input()) {
		pts::build();
		if (isReachableWithHop(S.r, S.c)) {
			cout << 0 << endl; continue;
		}
		for (int i : range(N)) {
			for (int j : range(4)) {
				g[i][j].clear();
				rg[i][j].clear();
				dist[i][j] = INF;
				rdist[i][j] = INF;
			}
		}
		buildGraph();
		bfs();
		
		for (int i : range(N)) {
			for (int j : range(4)) {
				const int r = in[i].r + dr[j];
				const int c = in[i].c + dc[j];
				if (isReachableWithHop(r, c)) {
					chmin(ret, dist[i][j]);
					isReachableWithHop(r, c);
				}
			}
		}

		for (int i : range(N)) {
			if (isReachable(S.r,S.c,S.r,in[i].c)) {
				const int r = S.r;
				const int c = in[i].c;
				if (Down::getIce(r, c) == i)
					chmin(ret, rdist[i][3 - Down::index] + 1);
				if (Left::getIce(r, c) == i)
					chmin(ret, rdist[i][3 - Left::index] + 1);

				if (Right::getIce(r, c) == i)
					chmin(ret, rdist[i][3 - Right::index] + 1);
				if (Up::getIce(r, c) == i)
					chmin(ret, rdist[i][3 - Up::index] + 1);
			}
			if (isReachable(S.r, S.c, in[i].r, S.c)) {
				const int r = in[i].r;
				const int c = S.c;
				if (Down::getIce(r, c) == i)
					chmin(ret, rdist[i][3 - Down::index] + 1);
				if (Left::getIce(r, c) == i)
					chmin(ret, rdist[i][3 - Left::index] + 1);
				if (Right::getIce(r, c) == i)
					chmin(ret, rdist[i][3 - Right::index] + 1);
				if (Up::getIce(r, c) == i)
					chmin(ret, rdist[i][3 - Up::index] + 1);
			}
		}
		solve_down();
		solve_up(); 
		solve_left();
		solve_right();
		if (ret == INF)cout << -1 << endl;
		else cout << ret << endl;
	}
	return 0;
}