#include <bits/stdc++.h>
using namespace std;
struct A
{
int c;
int v;
double p;
}a[105];
bool cmp(A s,A q)
{
return s.p>q.p;
}
int main()
{
int n,t;
double sum;
//cout<<setiosflags(ios::fixed)<<setprecision(2);
cin>>n>>t;
for(int i=1;i<=n;i++)
{
cin>>a[i].c>>a[i].v;
a[i].p=a[i].v/a[i].c;
}
sort(a+1,a+n+1,cmp);
int i=1;
while(t>0)
{
if(t>=a[i].c)
{
sum+=a[i].v;
t-=a[i].c;
}
else
{
sum+=a[i].p*t;
t=0;
}
i++;
}
cout<<sum;
}