int main(void)
{
    int n,m;
    cin>>n>>m;
    int k[n],k2[n];
    double k3[n],s=0;
    for(int i=0;i<n;i++)
    {
        cin>>k[i]>>k2[i];
        k3[i]=k2[i]/k[i];
    }
    while(m)
    {
        double max=-1.1;
        int max2=-1;
        for(int i=0;i<n;i++)
        {
            if(k3[i]>max)
            {
                max=k3[i];
                max2=i;
            }
        }
        if(m>k[max2])
        {
            s+=k2[max2];
            m-=k[max2];
            k[max2]=-1;
            k2[max2]=-1;
            k3[max2]=-1;
        }
        else
        {
            s+=m*max;
            printf("%.2f",s);
            return 0;
        }
    }
}