#include<bits/stdc++.h>
using namespace std;

struct coin{
	int m,v;
};
bool cmp(coin x,coin y)
{
	return x.v*y.m>y.v*x.m;
}
int main()
{
	coin a[110];
	int n,t,c,i;
	double ans=0;
	cin>>n>>t;
	c=t;
	for(i=0;i<n;i++)
	{
		cin>>a[i].m>>a[i].v;
	}
	sort(a,a+n,cmp);
	for(i=0;i<n;i++)
	{
		if(a[i].m>c)
		break;
		c-=a[i].m;
		ans+=a[i].v;
	}
	if(i<n)
	{
		ans=1.0*c/a[i].m*a[i].v;	 
	}
	printf("%.2lf",ans);
	return 0;
}

DALAO看一看 谢谢