#include <bits/stdc++.h>

#define MOD 1000000007
#define PI (2*acos(0.0))
#define eps 1e-9

#define ff first
#define ss second
#define pb push_back
#define endl '\n'
#define fu cout << "lol" << endl;
#define precision(n) cout << fixed << setprecision(n);
#define debug(x) cout << (#x) << " is " << (x) << endl;
#define printv(v) for(int fi = 0; fi < v.size(); fi++) cout << v[fi] << " "; cout << endl;
#define showpair(v) for(int fi = 0; fi < v.size(); fi++) cout << v[fi].first << " " << v[fi].second << endl;
#define all(a) a.begin(), a.end()
#define min3(a,b,c) min(a,min(b,c))
#define max3(a,b,c) max(a,max(b,c))
#define mem(a,val) memset(a,val,sizeof(a))

#define FORN(i, n) for(int i = ; i < n; i++)
#define REP(i, a, b) for(int i = a; i < b; i++)
#define SQ(a) (a)*(a)

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef vector<ll> vll;
typedef vector<ull> vull;
typedef pair<int, int> pi;
typedef vector<pi> vpi;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef vector<string> vs;
typedef vector<bool> vb;
typedef vector<vb> vbb;


ull mod = 1e9 + 7;
// ull mod = 998244353;

ull fact(ull n){
    ull ans = 1;
    for (ull i = 2; i <= n; i++)
        ans = ((ans%MOD) * (i%MOD) )%MOD;
    return ans;
}
ll powMod(ll base, ll exp){
    ll ans = 1;
    for (int i = 0; i < exp; i++)
    {
        ans*= base;
        ans %= mod;
    }
    return ans;
}
ll powMod(ll base, ll exp, ll md){
    ll ans = 1;
    for (int i = 0; i < exp; i++)
    {
        ans*= base;
        ans %= md;
    }
    return ans;
}



double solve(int D, int H, int d, int h){
    double slop = (double) (H - h)/(double) (D-d);
    double b = h - slop*d;
    return b;
}


void answer(){
    int n; cin >> n;
    int D, H; cin >> D >> H;
    vi d(n), h(n);
    double ans = 0;
    for (int i = 0; i < n; i++)
    {
        cin >> d[i] >> h[i];
        ans = max(ans, solve(D, H, d[i], h[i]));
    }
    cout << ans;
}
 
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout << setprecision(6) << fixed;

    int t = 1;
    // cin >> t; cin.ignore();
    while (t--)
    {
        answer();
    }
    return 0;
}
#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define fo(i,a,b) for(int i=a; i<b; i++)
#define vi vector<int>
#define vii vector<int,int> 
#define pi pair<int,int>
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define FASTIO ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);

int main(){
	FASTIO

	double d,h;
	int n;
	cin>>n>>d>>h;
	double minslope = h/d;
	double x1,y1;
	double tslope;
	fo(i,0,n){
		cin>>x1>>y1;
		tslope = (h-y1)/(d-x1);
		minslope = min(minslope,tslope);
	}
	double ans =  h - minslope*d;
	cout<<ans;



	return 0;
}
