/*
 * @Author: Luisvacson
 * @LastEditors: Luisvacson
 * @Descriptions: None
 * @Date: 2021-05-01 20:05:46
 * @LastEditTime: 2021-05-01 20:18:58
 * @FilePath: \C++\Practice\B.cpp
 */
#include <bits/stdc++.h>
using namespace std;
#define MAXN 1005

int n, d1, h1;
int d[MAXN], h[MAXN];
signed main() {
    scanf("%d%d%d", &n, &d1, &h1);
    register int i;

    double ans = -1;
    for (i = 1; i <= n; ++i) {
        scanf("%d%d", &d[i], &h[i]);
        int d2 = d[i], h2 = h[i];
        // printf("%d %d\n%d %d\n%d %d\n", h1, h2, d1, d2, h2 - h1, d2 - d1);
        double k = (double)((h2 - h1) * 1.0 / (d2 - d1));
        // printf("%.10lf\n", k);
        double b = h1 - k * d1;
        b = max(b, 0.0);
        ans = max(ans, b);
    }

    printf("%.10lf\n", ans);
    return 0;
}

#include <vector>
#include <list>
#include <map>
#include <set>
#include <climits>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <queue>

#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define per(i,a,b) for(int i=(a);i>(b);i--)
#define pb push_back
#define ff first
#define ss second
#define endl '\n'
#define mp make_pair
#define pb push_back
#define gap " "
#define vi vector<int>
#define ii pair<int,int>
#define vii vector<ii>
#define ldb long double



//memset(dp,-1,sizeof(dp)) sets value to -1 of everything in dp
//vector < vector<int > > vec(n,vector<int>(m,0)) here n are rows(top to down ) and m columns all with m vectors initialised with values 0 
//ARRAY OF VECTORS --> vector<int> ar[size] and to pass it in a function we use foo(vector<int>(&ar)[size]) 
//Number of digits in N =floor(log10(N)) + 1;  

typedef long long ll;
using namespace std;


int solve(){
    ldb n,D,H;
    cin>>n>>D>>H;
    ldb r=INT_MIN;
    rep(i,0,n)
    {
        ldb d,h;
        cin>>d>>h;
        r=max(r,(D*h-d*H)/(D-d));
    }
    if(r<0)
    {
        cout<<0.0<<endl;
        return 0;
    }
    cout<<r<<endl;
    return 0;

}
int main(){
#ifndef ONLINE_JUDGE
    freopen("input1.txt","r",stdin);
    freopen("output1.txt","w",stdout);
    #endif 
ios_base::sync_with_stdio(false); 
    cin.tie(NULL); 
int t=1;
while(t--){
      solve();
}
return 0;
}