#include<bits/stdc++.h>
using namespace std;
const int N=1e4+10;
struct Node{
	double xjb;
	double m,v;
};
Node a[N];
int n,t; 
bool cmp(Node x,Node y){
	return x.xjb>x.xjb;
}
int main(){
	scanf("%d%d",&n,&t);
	for(int i=1;i<=n;i++){
		cin>>a[i].m>>a[i].v;
		a[i].xjb=a[i].v/a[i].m;
	}
	sort(a+1,a+n+1,cmp);
	double jz=0.0,ak=0.0;
	int i=1;
	while(ak<t&&i-1<=n){
		ak+=a[i].m;
		jz+=a[i].v;
		i++;
	}
	i--;
	double str=ak-t;
	jz-=str*a[i].xjb;
	printf("%.2f",jz);
	return 0;
}