#include <bits/stdc++.h>

using namespace std;

long long N,l,U,tmp,cst,C[30100],T[30100],rc,rt;

int main(){ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	ifstream cin("secv3.in");
	ofstream cout("secv3.out");
	cin >> N >> l >> U;
	for(int i = 1;i<=N;i++)cin >> C[i],cst+=(i<l ? C[i] : 0);
	for(int i = 1;i<=N;i++)cin >> T[i],tmp+=(i<l ? T[i] : 0);
	for(int i = l;i<=N;i++){
		cst+=C[i];
		tmp+=T[i];
		if(!rt || rc*tmp < rt*cst) rc = cst, rt = tmp;
		cst-=C[i-l+1];
		tmp-=T[i-l+1];
	}
	
	cout << fixed << setprecision(2) << 1.0*rc/rt;
}