#include<bits/stdc++.h>

using namespace std;

#define endl "\n"
#define ll long long int

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
   
        ll n;
    cin>>n;
        double D,H;
        cin>>D>>H;
        
        double ans=0.0;
        
        while(n--)
        {
            double d,h;
            cin>>d>>h;
            double tan=(d*(H-h))/(D-d);
            tan=h-tan;
            ans=max(ans,tan);
        }
        cout<<setprecision(15)<<fixed<<ans<<endl;
   
    
    return 0;
}
#include "bits/stdc++.h"
using namespace std;

typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<long long> VL;
typedef vector<vector<long long>> VVL;
typedef pair<int,int> Pair;
typedef tuple<int,int,int> tpl;

#define ALL(a)  (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define REVERSE(c) reverse((c).begin(),(c).end())
#define EXIST(m,v) (m).find((v)) != (m).end()
#define LB(a,x) lower_bound((a).begin(), (a).end(), x) - (a).begin()
#define UB(a,x) upper_bound((a).begin(), (a).end(), x) - (a).begin()

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define RFOR(i,a,b) for(int i=(a)-1;i>=(b);--i)
#define RREP(i,n) RFOR(i,n,0)

#define en "\n"

constexpr double EPS = 1e-9;
constexpr double PI  = 3.1415926535897932;
constexpr int INF = 2147483647;
constexpr long long LINF = 1LL<<60;
constexpr long long MOD = 1000000007; // 998244353;

template<class T> inline bool chmax(T& a, T b){if(a<b){a=b;return true;}return false;}
template<class T> inline bool chmin(T& a, T b){if(a>b){a=b;return true;}return false;}

void Main(){
    int N; double D,H; cin >> N >> D >> H;
    VI d(N),h(N); REP(i,N) cin >> d[i] >> h[i];

    double ng = 0, ok = 1000;
    REP(_,50){
        double b = (ok+ng)/2;
        double a = (H-b)/D;
        bool flag = true;
        REP(i,N){
            if(a*d[i]+b < h[i]){
                flag = false;
                break;
            }
        }
        if(flag) ok = b;
        else ng = b;
    }
    cout << ok << en;
    return;
}

int main(void){
    cin.tie(0);cout.tie(0);ios_base::sync_with_stdio(0);cout<<fixed<<setprecision(15);
    int t=1; //cin>>t;
    while(t--) Main();
    return 0;
}