# define _GLIBCXX_DEBUG
# define rep(i, n) for (int i=0; i<(int)(n); i++)
# define FOR(i,a,b) for(int i=(a);i<=(b);++i)
# define ALL(a) (a).begin(), (a).end()
# define COUT(x) cout << (x) << endl;
# define KAI() cout << endl;
# define INF 10000000000000000LL
typedef long long ll;
# include <iostream>
# include <string>
# include <cmath>
# include <algorithm>
# include <vector>
# include <set>
# include <bitset>
# include <iomanip>
using namespace std;


int main() {
    int n;
    double D,H;
    cin >> n >> D >> H;

    vector<double> d(n);
    vector<double> h(n);
    
    rep(i,n) cin >> d[i] >> h[i];

    double ans=0.0;

    rep(i,n) {
        double temp;
        temp = (h[i]-H*d[i]/D)/(1.0-d[i]/D);
        // cout << "i=" << i << ", temp=" << temp << endl;
        if (temp < 0.0) continue;
        else ans = max(ans,temp);
    }
     cout << fixed << setprecision(15) << ans << endl;
}

#include<bits/stdc++.h>
using namespace std;
int main(){
	long double x,y,r;
	cin>>x>>y>>r;
	long long ans=0;
	r+=1e-14;
	for(long long i=ceil(x-r);i<=floor(x+r);i++)
	{
		long double t=sqrt(r*r-(i-x)*(i-x));//r'
		
		ans+=(floor(y+t))-(ceil(y-t))+1;
	}
	cout<<ans;
}