#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < (n); ++i)

int main() {
    int N; double D, H;
    cin >> N >> D >> H;
    double ans = 0;
    rep(i, N) {
        double d, h;
        cin >> d >> h;
        double y = d * (H - h) / (D - d);
        ans = max(ans, h - y);
    }
    cout << fixed << setprecision(10) << ans << '\n';
    return 0;
}

#include<bits/stdc++.h>
using namespace std;


#define ll long long
#define ld long double


#define lop(n) for(ll i=0;i<n;i++)
#define loop(a,b) for(ll i=a;i<b;i++)

#define sortt(x) sort(x.begin(),x.end())

#define MOD 1000000007
#define en "\n"


#define F first
#define S second


#define inputlist for(ll i=0;i<n;i++) cin>>A[i]
#define pb(x) push_back(x)
#define MP make_pair
#define PI 3.14159265

//SEGMENT TREE
/*
ll A[1000005],seg[3*1000005];

void build(ll ind,ll low,ll high)
{
    if(low==high)
    {
        seg[ind]=A[low];
        return;
    }
    ll mid=(low+high)/2;
    build(ind*2+1,low,mid);
    build(ind*2+2,mid+1,high);
    seg[ind]=(seg[ind*2+1]+seg[ind*2+2]);
}
ll query(ll ind,ll low, ll high, ll l, ll r)
{
    if(l<=low && r>=high)
        return (seg[ind]);
    if(low>r || high<l)
        return(0);
    ll mid=(low+high)/2;
    ll left=query(ind*2+1,low,mid,l,r);
    ll right=query(ind*2+2,mid+1,high,l,r);
    return(left+right);
}
*/

// 1 se 100 tk ka prime numbers hai inn dono mei
//ll x=1416919933790871510;
//ll y=1627168839228008057;

//fast power
ll fxp(ll base,ll expo)
{
    if(expo==0)
        return 1;
    if(expo%2==0)
    {
        ll c=fxp(base,expo/2);
        return((c*c)%MOD);
    }
    else
        return((base*fxp(base,expo-1))%MOD);
}
/*





bool isPrime(ll n)
{
    if (n <= 1)
        return false;
    if (n <= 3)
        return true;
    if (n % 2 == 0 || n % 3 == 0)
        return false;

    for (ll i = 5; i * i <= n; i = i + 6)
        if (n % i == 0 || n % (i + 2) == 0)
            return false;

    return true;
}



ll fact(ll n)
{
    return (n==1 || n==0) ? 1: n * fact(n - 1);
}
*/

// ll fac[200005];

// unsigned long long power(unsigned long long x, 
//                                   ll y, ll p)
// {
//     unsigned long long res = 1; // Initialize result
 
//     x = x % p; // Update x if it is more than or
//     // equal to p
 
//     while (y > 0) 
//     {
     
//         // If y is odd, multiply x with result
//         if (y & 1)
//             res = (res * x) % p;
 
//         // y must be even now
//         y = y >> 1; // y = y/2
//         x = (x * x) % p;
//     }
//     return res;
// }
 
// // Returns n^(-1) mod p
// unsigned long long modInverse(unsigned long long n,  
//                                             ll p)
// {
//     return power(n, p - 2, p);
// }
 
// // Returns nCr % p using Fermat's little
// // theorem.
// unsigned long long nCrModPFermat(unsigned long long n,
//                                  ll r, ll p)
// {
//     // If n<r, then nCr should return 0
//     if (n < r)
//         return 0;
//     // Base case
//     if (r == 0)
//         return 1;
 
//     // Fill factorial array so that we
//     // can find all factorial of r, n
//     // and n-r
 
//     return (fac[n] * modInverse(fac[r], p) % p
//             * modInverse(fac[n - r], p) % p)
//            % p;
// }








void solve()
{
    ll n,d,h;
    cin>>n>>d>>h;
    vector<pair<ll,ll>> vec;
    for(ll i=0;i<n;i++)
    {
        ll x,y;
        cin>>x>>y;
        vec.pb(MP(x,y));
    }
    sortt(vec);
    ld maxi = 1e18;
    for(ll i=0;i<n;i++)
    {
        ld kon = (h-vec[i].S)/(1.0*(d-vec[i].F));
        maxi = min(maxi, kon);
    }
    ld ans = maxi*(-1* d) + h;
    ans = max(ans, (ld)(0));
    cout<<fixed<<setprecision(15)<<ans<<en;
}


//536870912

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    //cin>>s;
    //call();
    // fac[0] = 1;
    // for (int i = 1; i <= 20000; i++)
    //     fac[i] = (fac[i - 1] * i) % MOD;
    ll t=1;
    // cin>>t;
    for(ll i=1;i<=t;i++)
    {
        // cout<<"Case #"<<i<<": ";
        solve();
    }
    return 0;
}
