#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>
#include <unordered_map>
using namespace std;

#define REP(i, s) for (int i = 0; i < s; ++i)
#define ALL(v) (v.begin(), v.end())
#define COUT(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << endl
#define EACH(i, s) for (__typeof__((s).begin()) i = (s).begin(); i != (s).end(); ++i)

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
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)
{ for (int i = 0; i < P.size(); ++i) { if (i > 0) { s << " "; } s << P[i]; } return s; }
template<class T> ostream& operator << (ostream &s, vector<vector<T> > P)
{ for (int i = 0; i < P.size(); ++i) { s << endl << P[i]; } return s << endl; }
template<class T> ostream& operator << (ostream &s, set<T> P)
{ EACH(it, P) { s << "<" << *it << "> "; } return s << endl; }
template<class T1, class T2> ostream& operator << (ostream &s, map<T1,T2> P)
{ EACH(it, P) { s << "<" << it->first << "->" << it->second << "> "; } return s << endl; }



const int MOD = 10007;
long long mod(long long a, int m) {
    return (a % m + m) % m;
}
inline long long inv(long long a, int m) {
    long long b = m, u = 1, v = 0;
    while (b) {
        long long t = a/b;
        a -= t*b; swap(a, b);
        u -= t*v; swap(u, v);
    }
    return mod(u, m);
}

template<class T> struct Matrix {
    vector<vector<T> > val;
    Matrix(int n = 1, int m = 1) {val.clear(); val.resize(n, vector<T>(m));}
    Matrix(int n, int m, T x) {val.clear(); val.resize(n, vector<T>(m, x));}
    void init(int n, int m, T x = 0) {val.clear(); val.resize(n, vector<T>(m, x));}
    void resize(int n, int m, T x = 0) {val.resize(n); for (int i = 0; i < n; ++i) val[i].resize(m, x);}
    int size() {return val.size();}
    inline vector<T>& operator [] (int i) {return val[i];}
    friend ostream& operator << (ostream& s, Matrix<T> M) {s << endl; 
        for (int i = 0; i < M.val.size(); ++i) s << M[i] << endl; return s;}
};

template<class T> int Rank(Matrix<T> A, int p) {
	int rank = 0;
	/*
    for (int i = 0; i < A.size(); ++i) 
        for (int j = 0; j < A[0].size(); ++j)
            A[i][j] = mod(A[i][j], p);
	*/
    
	T res = 1;
	for (int i = 0; i < A[0].size(); ++i) {
		int pivot = rank;
        bool exist = false;
        for (int j = rank; j < A.size(); ++j) {
            if (A[j][i] != 0) {
                pivot = j;
                exist = true;
                break;
            }
        }
		if (exist) {
			swap(A[pivot], A[rank]);
			res = mod(res * A[rank][i], p);
            T ainv = inv(A[rank][i], p);
			vector<T> tmp(A[0].size());
            for (int j = 0; j < A[0].size(); ++j) {
                tmp[j] = mod(A[rank][j] * ainv, p);
            }
			for (int j = 0; j < A.size(); ++j) {
				if (j != rank && A[j][i] != 0) {
                    T fac = A[j][i];
					for (int k = 0; k < A[0].size(); ++k) {
                        A[j][k] = mod(A[j][k] - tmp[k] * fac, p);
                    }
				}
			}
			++rank;
        }
        //else return 0;
	}

    return rank;
};


unsigned int randInt() {
    static unsigned int tx = 123456789, ty=362436069, tz=521288629, tw=88675123;
    unsigned int tt = (tx^(tx<<11));
    tx = ty; ty = tz; tz = tw;
    return ( tw=(tw^(tw>>19))^(tt^(tt>>8)) );
}  

int randInt(int minv, int maxv) {
    return randInt() % (maxv - minv + 1) + minv;
}


int N, A, B;
int a[2100], b[2100];

int main() {
  while (cin >> N >> A >> B) {
	for (int i = 0; i < N; ++i) cin >> a[i] >> b[i];

	vector<int> dame;
	for (int i = 0; i < N; ++i) {
	  if (abs(a[i] - b[i]) <= A
		  || (abs(a[i]-b[i]) >= B && abs(a[i]-b[i]) <= A*2))
		continue;
	  dame.push_back(i);
	}

	if (dame.empty()) {
	  cout << N << endl;
	  continue;
	}

	int V = dame.size();

	Matrix<int> M(V, V, 0);
	int iter = 0;
	for (int i = 0; i < dame.size(); ++i) {
	  for (int j = i + 1; j < dame.size(); ++j) {
		int u = dame[i], v = dame[j];
		int dist = abs(a[u] + a[v] - b[u] - b[v]);
		if (dist <= A || (dist >= B && dist <= A*2)) {
		  int ran = randInt(1, MOD-1);
		  M[i][j] = ran;
		  M[j][i] = MOD - ran;
		}
	  }
	}

	/*
	COUT(dame);
	COUT(M);
	*/

	int rank = Rank(M, MOD);

	//COUT(rank);
	
	int res = rank/2 + (N - (int)dame.size());
	cout << res << endl;
	//COUT(single); 

	/*
	Matrix<int> M(V, V, 0);
	for (int i = 0; i < single.size(); ++i) {
	  int u = single[i];
	  int v = N + i;
	  int ran = randInt(1, MOD-1);
	  M[u][v] = ran;
	  M[v][u] = MOD - ran;
	}
	
	
	//Matrix<int> M(N, N, 0);
	for (int i = 0; i < N; ++i) {
	  for (int j = i+1; j < N; ++j) {
		int dist = abs(a[i] + a[j] - b[i] - b[j]);
		if (dist <= A || (dist >= B && dist <= A*2)) {
		  int ran = randInt(1, MOD-1);
		  M[i][j] = ran;
		  M[j][i] = MOD - ran;
		}
	  }
	}
	

	//COUT(M);

	int res = Rank(M, MOD);
	//COUT(res);

	*/
  }
   
}



















Measured memory_bytes: 7372