#include<bits/stdc++.h>

using namespace std;

struct jb
{
	int jz,zl;
	double dj;
}hdjb[100001];

int n,t,b;

double res;

bool cmp(jb sa,jb sb)
{
	if(sa.dj<sb.dj)
	{
		return false;
	}
	else
	{
		return true;
	}
}

int main()
{
	cin>>n>>t;
	for(int i=1;i<=n;i++)
	{
		cin>>hdjb[i].zl>>hdjb[i].jz;
		hdjb[i].dj=hdjb[i].jz/hdjb[i].zl;
	}
	sort(hdjb+1,hdjb+n+1,cmp);
	b=1;
	while(t>hdjb[b].zl)
	{
		t-=hdjb[b].zl;
		res+=hdjb[b].jz;
		b++;
	}
	while(t>0)
	{
		t-=1;
		res+=hdjb[b].dj;
	}
	printf("%.2lf",res);
	return 0;
}