#include <bits/stdc++.h>
#define ll long long
#define md 1000000007
using namespace std;
int main(){
ll n,H,D,d,h,i;
double mx=0;

cin>>n>>D>>H;

for(i=0;i<n;i++){
	cin>>d>>h;
	if(H*d>=h*D) continue;
	double numr = h*D - H*d;
	double den = D-d;
	double val = numr/den;
	mx = max(mx,val);
}
cout.precision(10);
cout<<fixed<<mx;
	return 0;
}
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef long double ld;
typedef pair<ll, ll> pll;
#define FOR(i, a, b) for(int i = a; i < b; i++)
#define ROF(i, a, b) for(int i = a; i >= b; i--)
#define ms memset
#define pb push_back
#define F first
#define S second
ll MOD = 1000000007;

ll power(ll base, ll n){
	if (n == 0) return 1;
	if (n == 1) return base;
	ll halfn = power(base, n/2);
	if (n % 2 == 0) return (halfn * halfn) % MOD;
	return (((halfn * halfn) % MOD) * base) % MOD;
}
 
ll inverse(ll n){
	return power(n, MOD-2);
}
 
ll add(ll a, ll b){
	return (a+b) % MOD;
}

ll mul(ll a, ll b){
	return (a*b) % MOD;
}

ll gcd(ll a, ll b){
	if (a == 0) return b;
	if (a == 1) return 1;
	return gcd(b%a, a);
}

const int N = (1<<18) + 1;
vi p(N), r(N);
int get(int a){
	return p[a] = (p[a] == a ? p[a] : get(p[a]));
}
void Union(int a, int b){
	int c = get(a); int d = get(b);
	if (c == d) return;
	if (r[c] == r[d]) r[c]++;
	if (r[c] > r[d]){
		p[d] = c;
	}else{
		p[c] = d;
	}
}
int main(){
    ios::sync_with_stdio(false);
    int n; ld d, h; cin >> n >> d >> h;
    ld grad = h / d;
	FOR(i, 0, n){
		ld h1, d1; cin >> d1 >> h1;
		grad = min( (h-h1)/(d-d1), grad); 
	}
	ld ans = h - grad * d;
	cout << setprecision(18) << ans << '\n';
	return 0;
}


