#include <bits/stdc++.h>
using namespace std;
typedef long long lint;
#define rep(i,n) for(lint (i)=0;(i)<(n);(i)++)
#define repp(i,m,n) for(lint (i)=(m);(i)<(n);(i)++)
#define repm(i,n) for(lint (i)=(n-1);(i)>=0;(i)--)
#define INF (1ll<<60)
#define all(x) (x).begin(),(x).end()
const lint MOD =1000000007;
//const lint MOD=998244353;
const lint MAX = 4000000;
using Graph =vector<vector<lint>>;
typedef pair<lint,lint> P;
typedef map<lint,lint> M;
#pragma GCC optimize("Ofast")
#define chmax(x,y) x=max(x,y)
#define chmin(x,y) x=min(x,y)
 
 
lint fac[MAX], finv[MAX], inv[MAX];
 
void COMinit() 
{
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (lint i = 2; i < MAX; i++)
    {
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}
 
long long COM(lint n, lint k)
{
    if (n < k)
        return 0;
    if (n < 0 || k < 0)
        return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
 
lint primary(lint num)
{
    if (num < 2) return 0;
    else if (num == 2) return 1;
    else if (num % 2 == 0) return 0;
 
    double sqrtNum = sqrt(num);
    for (int i = 3; i <= sqrtNum; i += 2)
    {
        if (num % i == 0)
        {
            return 0;
        }
    }
 
    return 1;
}
   long long modpow(long long a, long long n, long long mod) {
    long long res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}
    lint lcm(lint a,lint b){
        return a/__gcd(a,b)*b;
    }
     lint gcd(lint a,lint b){
        return __gcd(a,b);
    }


    int main(){
        lint n,d,h;
        cin>>n>>d>>h;
        P p[n];
     double ans=0;
        rep(i,n){
            lint a,b;
            cin>>a>>b;
            long double kata=(double)(h-b)/(d-a);
            ans=max(ans, double(h-kata*d));

            
        }


    printf("%.12f\n",ans);



        }
        
       


    

      
///Bishmillahir Rahmanir Rahim,In the name of Almighty Allah(swt)
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define lop(i,n) for(i=0;i<n;i++)
#define lop1(i,n) for(i=1;i<=n;i++)
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define pi 3.14159265358979323846
#define smile ios_base::sync_with_stdio(false);	cin.tie(NULL);
//void file();
//void error();

int main()
{
	smile        //file();

	int t;
//	cin >> t;
//	for (int z = 1; z <= t; z++) {

	int n, i, j;
	int a[2][2];
	lop(i, 2) {
		lop(j, 2)
		cin >> a[i][j];
	}

	int b,c;
	b = a[0][0]*a[1][1];
	c = a[0][1]*a[1][0];
cout<<b-c<<endl;







//	}

//error();
	return 0;
}

/*
void file() {
#ifndef ONLINE_JUDGE
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
	freopen("error.txt", "w", stderr);
#endif
}
void error()
{
	cerr << "time taken : " << (float)clock() / CLOCKS_PER_SEC << " secs" << endl;
}

*/