#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using ll = long long;
using namespace std;
 
int main(){
    int n, D, H;
    cin >> n >> D>> H;
    double ans = 0;
    rep(i, n){
        int d, h;
        cin >> d >> h;
        double now = H - double (H-h) * D/ (D-d);
        ans = max(ans, now);
    }
    printf("%.10f\n", ans);
    return 0;
}
#include <bits/stdc++.h>

using namespace std;
// using ll = long long;
#define int long long

void solve(){
	int n, d, h;
	cin>>n>>d>>h;
	vector<pair<int,int>> a(n);
	for(int i=0;i<n;i++){
		cin>>a[i].first>>a[i].second;
	}
	sort(a.begin(), a.end());
	double ans = 0;
	for(int i=0;i<n;i++){
		double now = double(a[i].second - h)/ double(a[i].first - d);
		ans = max(ans, a[i].second - now*a[i].first);
	}
	cout<<fixed<<setprecision(10);
	cout<<ans<<"\n";
}
int32_t main(){
	ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);

	int t;
	// cin>>t;
	t = 1;
	int _=1;
	while(t--){
		// cout<<"Case #"<<_++<<": ";
		solve();
	}
	return 0;
}