#include <algorithm>
#include <iomanip>
#include <iostream>
using ld = long double;

int main() {
  std::cout << std::fixed << std::setprecision(16);
  int N;
  ld D, H, res = -1.0;
  std::cin >> N >> D >> H;

  ld d, h, y;
  for (int i = 0; i < N; i++) {
    std::cin >> d >> h;
    y = ((h - H) * (-1 * D)) / (d - D);
    y+=H;
    // std::cout << y << '\n';
    res = std::max(res, y);
  }
  ld t = 0.00;
  res = std::max(res, t);
  std::cout << res << '\n';
}
#include<bits/stdc++.h>

typedef long long int lli;
typedef long double lld;
typedef long long ll;

//Fast Input I/O
#define fio ios_base::sync_with_stdio(false), cin.tie(NULL);
//Datatype
#define vi vector<int>
#define vlli vector<long long int>
#define vvi vector<vector<int>>
#define vvlli vector<vector<long long int>>
#define ppi pair<int, int>
#define rppi pair<int, pair<int, int>>
#define lppi pair<pair<int, int>, int>
#define vppi vector<pair<int, int>>
#define sppi stack<pair<int int>>
#define qppi queue<pair<int, int>>
//function
#define f first
#define s second
#define pb(x) push_back(x)
#define mkp(i, j) make_pair(i, j)
#define lmkp(i,j,k) make_pair(make_pair(i,j),k)
#define rmkp(i,j,k) make_pair(i,make_pair(j,k))
//loop
#define loop(i,n) for (i = 0; i < n; ++i)
#define loops(i,k,n) for (i = k; i <= n; ++i)
#define looprev(i,k,n) for (i = k; i >= n; --i)
//Const
#define inf (int)1e9
#define eps 1e-9
#define PI 3.1415926535897932384626433832795
#define MOD 1000000007
//Print
#define prd(n) printf("%d", n)
#define prl(n) printf("%lld", n)
#define prdn(n) printf("%d\n", n)
#define prln(n) printf("%lld\n", n)
#define prf(n) printf("%f", n)
//Scan
#define scd(n) scanf("%d", &n)
#define scd2(a, b) scanf("%d %d", &a, &b)
#define scd3(a, b, c) scanf("%d %d %d", &a, &b, &c)
#define scl(n) scanf("%lld", &n)
#define scl2(a, b) scanf("%lld %lld", &a, &b)
#define scl3(a, b, c) scanf("%lld %lld %lld", &a, &b, &c)
#define scf(n) scanf("%f", &n)
#define all(x) (x).begin(), (x).end()

using namespace std;
void online_judge() {
#ifndef ONLINE_JUDGE
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
}


void solve() {
	lli i, j, k;
	lld N, D, H, res = 0;
	cin >> N >> D >> H;
	loop(i, N) {
		lld d, h;
		cin >> d >> h;
		lld x = H - ((H - h) * D) / (D - d);
		res = max(res, x);
	}
	cout << res << "\n";
}

int main() {
	fio;
	online_judge();
	cout << fixed << setprecision(20);
	lli t = 1;
	//cin >> t;
	while (t--) {
		solve();
	}
	return 0;
}

