#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;
typedef struct
{
    int c,t;
}ceva;
int n,l,u;
double x,mx=0;
int cost[30005],timp[30005];
int CostSuma[100005];
int TimpSuma[100005];
int main()
{
    ifstream in("secventa3.in");
    ofstream out("secventa3.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)
    {
        for (int j=i;j<=i+u-1;++j)
        {
           x=CostSuma[j]/TimpSuma[j];
           if (mx<x) mx=x;
        }
    }
    out <<setprecision(2)<<mx;
    return 0;
}