#include <bits/stdc++.h>
using namespace std;
 
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
 
int main() {
  double ans;
  int N;
  double D, H;
  double delta;
  double dN, hN;
 
  cin >> N >> D >> H;
  ans = 0;
  rep(i, N){
      cin >> dN >> hN;
      delta = (H - hN) / (D - dN);
      ans = max(ans, (H - delta * D) );
  }
   cout << fixed << setprecision(13) << ans << endl;
}
#include <bits/stdc++.h>
using namespace std;
int d[105],h[105];
int main()
{
	int N,D,H;
	double max=-1;
	cin>>N>>D>>H;
	for(int i=0;i<N;i++)
	{
		scanf("%d%d",&d[i],&h[i]);
		double x1=D,y1=H,x2=d[i],y2=h[i];
		double b=y1-((x1*y1-x1*y2)*1.0/(x1-x2));
		if(b>=0)
		{
			if(b>max)
			{
				max=b;
			}
		}
	}
	if(max==-1)//b都是小于0的 
	{
		printf("0.0");
	}
	else{
		printf("%.8f",max);
	}
	
}