p2240

#include<bits/stdc++.h>
using namespace std;
struct coin{
	int m,v;
}a[1000];
bool cmp(coin x,coin y){
	return x.v*y.m>y.v*x.m;
}
int main(){
	int n,t,c,i;
	double ans=0;
	scanf("%d%d",&n,&t);
	c=t;
	for(i=0;i<n;i++)
	    scanf("%d%d",&a[i].m,&a[i].v);
	sort(a,a+n,cmp);
	for(int i=0;i<n;i++){
		if(a[i].m>c) break;
		c-=a[i].m;
		ans+=a[i].v;
	}
	if(i<n)
	    ans+=1.00*c/a[i].m*a[i].v;
	printf("%.2ld",ans);
	return 0;
}