#include <bits/stdc++.h>
#define nmax 1005
using namespace std;
int g[nmax],n,v[nmax],gmax;
struct Dublu
{
    double greutate;
    int val;
};
Dublu t[nmax];
inline bool Sortare(const Dublu A,const Dublu B)
{
    return A.val*B.greutate>A.greutate*B.val;
}
void Citire()
{
    int i;
    cin>>n>>gmax;
    for(i=1;i<=n;i++)
        cin>>t[i].greutate>>t[i].val;
    sort(t+1,t+n+1,Sortare);
}
void Rezolvare()
{
    int i;
    double sol=0;
    for(i=1;i<=n && gmax>=t[i].greutate;i++)
    {
        gmax-=t[i].greutate;
        sol+=t[i].val;
    }
    if(i<=n)
        sol+=(double)(gmax*t[i].val)/t[i].greutate;
    cout<<setprecision(3)<<fixed<<sol<<"\n";
}
int main()
{
    Citire();
    Rezolvare();
    return 0;
}