#include<bits/stdc++.h>
using namespace std;
struct c
{
	int t,b;
	double z=b/t;
}a[1000];
bool cmp(c a,c b)
 {
    return a.z < b.z;
}
int main()
{
	int n,t;
	double sum,bi,w;
	scanf("%d%d",&n,&t);
	for(int i=1;i<=n;i++)
	   scanf("%d%d",&a[i].t,&a[i].b);
    sort(a,a+n,cmp);
    
    int i;
    while(sum<t)
    {
    	bi+=a[i].z*a[i].t;
		sum+=a[i].t;
    	i++;
    
	}
	w=sum-t;
	bi=w*a[i-1].z;
	printf("%.2d",bi);
	return 0;
}