Problem: Dr. Kay Em, a genius scientist, developed a new missile named "Ikan-no-i." This missile has N jet engines. When the i-th engine is ignited, the missile's velocity changes to (vxi, vyi) immediately.

Your task is to determine whether the missile can reach the given target point (X, Y ). The missile can be considered as a mass point in a two-dimensional plane with the y-axis pointing up, affected by the gravity of 9.8 downward (i.e. the negative y-direction) and initially set at the origin (0, 0). The engines can be ignited at any time in any order. Still, note that at least one of them needs to be ignited to get the missile launched.



Input

The input consists of multiple datasets. Each dataset has the following format.

N
vx1 vy1
vx2 vy2
...
vxN vyN
X Y


All values are integers and meet the following constraints: 1 ≤ N ≤ 1,000, 0 < vxi ≤ 1,000, -1,000 ≤ vyi ≤ 1,000, 0 < X ≤ 1,000, -1,000 ≤ Y ≤ 1,000.

The end of input is indicated by a line with a single zero.

Output

For each dataset, output whether the missile can reach the target point in a line: "Yes" if it can, "No" otherwise.

Example

Input

1
1 1
10 -480
2
6 7
5 5
4 1
3
10 5
4 4
8 4
2 0
0


Output

Yes
Yes
No

Solution (in CPP):

Solution:
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <ctime>
#include <cstring>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <numeric>
#include <utility>
#include <iomanip>
#include <algorithm>
#include <functional>
using namespace std;

typedef long long ll;
typedef vector<int> vint;
typedef vector<ll> vll;
typedef pair<int,int> pint;

#define DE 1
#define FI first
#define SE second
#define PB push_back
#define MP make_pair
#define ALL(s) (s).begin(),(s).end()
#define REP(i,n) for (int i = 0; i < (int)(n); ++i)
#define EACH(i,s) for (__typeof__((s).begin()) i = (s).begin(); i != (s).end(); ++i)
#define COUT(x) cout<<#x<<" = "<<(x)<<" (L"<<__LINE__<<")"<<endl

template<class T1, class T2> ostream& operator<<(ostream &s, pair<T1,T2> P){return s<<'<'<<P.first<<", "<<P.second<<'>';}
template<class T> ostream& operator<<(ostream &s, vector<T> P) {s<<"{ ";for(int i=0;i<P.size();++i){if(i>0)s<<", ";s<<P[i];}return s<<" }"<<endl;}
template<class T1, class T2> ostream& operator<<(ostream &s, map<T1,T2> P) {s<<"{ ";for(__typeof__(P.begin()) it=P.begin();it!=P.end();++it){if(it!=P.begin())s<<", ";s<<'<'<<it->first<<"->"<<it->second<<'>';}return s<<" }"<<endl;}



typedef double DD;
const DD INF = 1LL<<29;
const DD EPS = 1e-7;
const DD g = 9.8;

struct Para {
	DD f, s, t;
    Para(DD f_ = 0.0, DD s_ = 0.0, DD t_ = 0.0) : f(f_), s(s_), t(t_) {}
};
ostream& operator<<(ostream &s, const Para &p) {
    return s << '<' << p.f << " ; " << p.s << " : " << p.t << '>' << endl;
}
bool operator < (Para p, Para q) {
    return (p.s < q.s);
}
bool operator > (Para p, Para q) {
    return (p.s > q.s);
}

Para makepara(DD vx, DD vy) {
    DD f = -g/2/vx/vx;
    DD s = vy/vx;
    DD t = 0.0;
    return Para(f, s, t);
}

Para envelope(Para p1, Para p2) {
    DD a = p1.f, b = p1.s, c = p1.t;
    DD p = p2.f, q = p2.s, r = p2.t;
    DD f = p*a/(p+a);
    DD s = (p*b+q*a)/(p+a);
    DD t = r+c-(q-b)*(q-b)/4/(p+a);
    return Para(f, s, t);
}

int N;
DD X, Y;
vector<Para> engine;
vector<Para> upline;
vector<pair<DD,DD> > divid;

int main() {
    while (cin >> N) {
        if (N == 0) break;
        
        engine.clear(); upline.clear(); divid.clear();
        for (int i = 0; i < N; ++i) {
            DD vx, vy; cin >> vx >> vy;
            Para p = makepara(vx, vy);
            engine.PB(p);
        }
        cin >> X >> Y;
        
        //COUT(engine);
        sort(ALL(engine), greater<Para>());
        //COUT(engine);
        
        bool isdown = false, isup = false;
        for (int i = 0; i < N; ++i) {
            Para p = engine[i];
            DD h = p.f*X*X + p.s*X + p.t;
            if (Y - h > -EPS) isdown = true;
        }
        
        Para now = engine[0];
        upline.PB(now); divid.PB(MP(0.0, INF));
        for (int i = 1; i < N; ++i) {
            Para p = engine[i];
            DD se = (p.s - now.s)/2/now.f;
            now = envelope(now, p);
            
            upline.PB(now);
            divid[i-1].SE = se;
            divid.PB(MP(se, INF));
        }
        
        //COUT(upline);
        //COUT(divid);
        
        for (int i = 0; i < N; ++i) {
            if (divid[i].FI - EPS < X && X < divid[i].SE + EPS) {
                Para p = upline[i];
                DD h = p.f*X*X + p.s*X + p.t;
                
                //cout << i << " : " << h << endl;
                
                if (h - Y > -EPS) isup = true;
            }
        }
        
        //COUT(isdown); COUT(isup);
         
        if (isdown && isup) cout << "Yes" << endl;
        else cout << "No" << endl;
    }
    
    return 0;
}