//#pragma GCC optimize ("Ofast")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("avx,avx2,fma")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
#define pb push_back
#define F first
#define S second
#define ins insert
#define mp make_pair
#define fo(i, n1, n, x) for(int i = n1; i <= n; i += x)
#define foo(i, n, n1, x) for(int i = n; i >= n1; i -= x)
#define bit __builtin_popcount
#define md (l + ((r - l) / 2))
#define all(x) x.begin(),x.end()
#define eb emplace_back
#define ub upper_bound
#define lb lower_bound
#define ios ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define file(s) if (fopen(s".in", "r")) freopen(s".in", "r", stdin), freopen(s".out", "w", stdout)

using namespace std;
//using namespace __gnu_pbds;
//using namespace __gnu_cxx;


using ll = long long;

//#define int ll

using pii = pair<int,int>;
using pll = pair<ll,ll>;
using vi = vector<int>;



const int N = 2e5 + 11, mod = 1e9 + 7, mod2 = 998244353;
const int MAX = 1e5 + 11;
const int INF1 = 2e9 + 11;
const ll INF2 = 6e18 + 11;
const double INF3 = 1e8 + 11;
const int base = 500;
const int P = 31;
const int dx[] = {1, -1, 0, 0, 1, 1, -1, -1};
const int dy[] = {0, 0, 1, -1, 1, -1, 1, -1};
const double EPS = 1e-4;
const double PI = acos(-1.0);


//template<typename T> using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T1, typename T2> inline void chmin(T1 &a, T2 b) { if (a > b) a = b; }
template<typename T1, typename T2> inline void chmax(T1 &a, T2 b) { if (a < b) a = b; }


mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int rnd(int l, int r) { return uniform_int_distribution<int> (l, r)(rng); }

int n;
double D, H, h[111], d[111];
bool can(double x) {
  fo(i, 1, n, 1) {
    double slope = (H - x) / D;
    double he = x + (d[i] * slope);
    if (h[i] > he) return 0;
  }
  return 1;
}
main() {
  file("paint");
  ios;
  cin >> n >> D >> H;
  fo(i, 1, n, 1) cin >> d[i] >> h[i];
  double l = 0, r = H;
  while (r - l > EPS)  {
    can(md) ? r = md : l = md;
  }
  cout << fixed << setprecision(12) << md;
  return 0;
}
/**

*/

#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#define ll long long
#define mod 1000000007

// templates
#define all(v) v.begin(), v.end()
#define F first
#define S second
#define sz(x) (int)x.size()
#define po(x, y) fixed << setprecision(y) << x
#define ss(s) scanf(" %[^\n]%*c", s)
#define sc(n) scanf("%d", &n)
#define sl(n) scanf("%lld", &n)
#define ps(s) printf("%s\n", s)
#define pr(n) printf("%d\n", n)
#define pl(n) printf("%lld\n", n)
#define prs(n) printf("%d ", n)
#define pls(n) printf("%lld ", n)
using namespace std;

const ll inf = (ll)1e15 + 10;
const int N = (int)1e6 + 10;

void solve() {
  int N, D, H;
  sc(N), sc(D), sc(H);
  vector<pair<int, int>> v;
  for (int i = 0; i < N; i++) {
    int d, h;
    sc(d), sc(h);
    v.push_back({d, h});
  }
  double mx = 0.0;
  for (auto x : v) {
    double temp = ((H - x.S) * 1.0 * D) / ((D - x.F));
    mx = max(mx, H - temp);
  }
  printf("%0.6f", mx);
}

int main() {
  // #ifndef ONLINE_JUDGE
  // 	freopen("input.txt", "r", stdin);
  // 	freopen("output.txt", "w", stdout);
  // #endif
  int t = 1;
  // sc(t);
  while (t--) {
    solve();
  }
  //	cerr << (float)clock() / CLOCKS_PER_SEC * 1000 << " ms" << endl;
  return 0;
}