#include <iostream>
#include <fstream>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <vector>
#define For(i,a,b) for (int i=(a);i<=(b);++i)

using namespace std;
int n,l,u;
double x,mx=0;
double cost[30005],timp[30005];
double CostSuma[100005];
double TimpSuma[100005];
int main()
{
    ifstream in("secv3.in");
    ofstream out("secv3.out");
    in >>n>>l>>u;
    For(i,1,n)
    {
        in >>cost[i]>>timp[i];
        CostSuma[i]=CostSuma[i-1]+cost[i];
        TimpSuma[i]=TimpSuma[i-1]+timp[i];
    }
    For(i,1,n-u+1)
    {
        double sf=min(n,i+min(l-1,u+1000));
        for (int j=i+u-1;j<=sf;++j)
        {
           x=CostSuma[j]-CostSuma[i-1]/TimpSuma[j]-TimpSuma[i-1];
           if (mx<x) mx=x;
        }
    }
    out <<setprecision(2)<<mx;
    return 0;
}