#include <bits/stdc++.h>

using namespace std;
struct obiect{
int g,v;
double r;
}O[1010];
int Gmax,i,j,n;
double Suma;

int DupaRaport(obiect A, obiect B)
{
    return A.r > B.r;
}
int main()
{
    cin>>n>>Gmax;
    for(i=1; i<=n; i++)
    {
        cin>>O[i].g>>O[i].v;
        O[i].r= 1.0*O[i].v/O[i].g;
    }
    sort(O + 1, O+n+1, DupaRaport);
    i=1;
    while(Gmax>=O[i].g && i<=n)
    {
        Suma+=O[i].v;
        Gmax-=O[i].g;
        i++;
    }
    if(Gmax>0 && i<=n)
        Suma +=1.0*Gmax*O[i].v/O[i].g;
    cout<<Suma;
    return 0;
}