#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
struct val
{
	int m;
	int v;
}par[110];
bool cmp(val a,val b)
{
	int x=a.m*b.v;
	return a.m*b.v>b.m*a.v;
}
int main()
{
	int n,t;
	double ans=0;
	scanf("%d%d",&n,&t);
	for(int i=1;i<=n;i++)
	scanf("%d%d",&par[i].m,&par[i].v);
	sort(par+1,par+1+n,cmp);
	for(int i=1;i<=n;i++)
	{
		if(par[i].m<=t) ans+=par[i].v,t-=par[i].m;
		else{
			ans+=par[i].v*t*1.0/(par[i].m*1.0);
			break;
		}
	}
	printf("%.2f",ans);
	return 0;
}