#include <fstream>
#define x first
#define y second
#define DIM 50002
using namespace std;

int f[DIM], S[DIM], D[DIM], PS[DIM], PD[DIM], minim[3];
int n, dx, dy, t, i, st;
pair<int, int> p[DIM];
int main () {
    ifstream fin ("tribute.in");
    ofstream fout("tribute.out");
    fin>>n>>dx>>dy;

    for (i=1;i<=n;i++)
        fin>>p[i].x>>p[i].y;

    for (t = 1; t <= 2; t++) {
        for (i=0;i<=50000;i++)
            f[i] = 0;
        for (i=1;i<=n;i++)
            if (t == 1)
                f[ p[i].x ]++;
            else
                f[ p[i].y ]++;

        S[0] = 0;
        PS[0] = f[0];
        for (i=1;i<=50000;i++) {
            S[i] = S[i-1] + PS[i-1];
            PS[i] = PS[i-1] + f[i];
        }
        D[50000] = 0;
        PD[50000] = f[50000];
        for (i=49999; i>=0; i--) {
            D[i] = D[i+1] + PD[i+1];
            PD[i] = PD[i+1] + f[i];
        }

        minim[t] = 2000000000;
        for (st = 0; st + dx <= 50000; st++)
            if (minim[t] > S[st] + D[st+dx])
                minim[t] = S[st] + D[st+dx];

        dx = dy;
    }

    fout<<minim[1] + minim[2];

    return 0;
}