#include <iostream>
#include <fstream>
using namespace std;
ifstream f("date.in");
int n,GMax;
struct elem
{
    float R,G,V;
};
elem a[100],auxiliar;
void citire()
{
    f >> n >> GMax;
    for(int i=1;i<=n;i++)
        {f >> a[i].G >> a[i].V;
        a[i].R = a[i].V/a[i].G;
}
}
int sortare(int st,int dr)
{int aux,di,dj,i,j;
i=st;
j=dr;
di=0;
dj=1;
while(i<j)
    {
        if(a[i].R<a[j].R)
        {
            auxiliar=a[i];
            a[i]=a[j];
            a[j]=auxiliar;
            aux=di;
            di=dj;
            dj=aux;
        }
        i=i+di;
        j=j-dj;
    }
    return i;
}
void quick(int st, int dr)
{int x;
if(st<dr)
    {
        x=sortare(st,dr);
        quick(st,x-1);
        quick(x+1,dr);
    }
}
void rezolva(int GMax)
{int k=1;
int Gcur=0;
int Vmax=0;
float Frc;
    while(Gcur<GMax)
    {
        if(Gcur+a[k].G>GMax)
        {
            Frc=((a[k].G-(GMax-Gcur))/(a[k].G*1.0))*a[k].V;
            Vmax = Vmax + Frc;
            Gcur = Gcur + (GMax-a[k].G);
        }
        else
        {
        Gcur=Gcur+a[k].G;
        Vmax=Vmax+a[k].V;
        }
        k++;
    }
cout << Vmax;
}
int main()
{
    citire();
    quick(1,n);
    rezolva(GMax);
    return 0;
}