#include<cstdio> 
#include<algorithm>
#include<iostream>
using namespace std;

struct coin{
		int m;
		int v;
	} a[1001];

bool cmp(coin x,coin y)
{
	return(x.v*y.m>x.m*y.v);
}

int main()
{
	int N;
	cin>>N;
	int T;
	cin>>T;
	
	for(int i=0;i<N;i++)
	{
		cin>>a[i].m>>a[i].v;
	}
	
	sort(a,a+N,cmp);
	
	int nowsum=0;
	double price=0;
	
	for(int i=0;i<N;i++)
	{
		if(nowsum+a[i].m>T)
		{
			printf("%.2lf",price+(T-nowsum)*a[i].v*1.0/a[i].m);
			break;
		}
		else
		{
			price+=a[i].v;
			nowsum+=a[i].m;
		}
		
		
	}
	
	if(nowsum<=T) printf("%.2lf",price);
	return 0;
}