#include<bits/stdc++.h>
using namespace std;
double a[101],b[101],c[101];
double ans;
int n,m;
bool cmp(double x,double y)
{
	return x>y;
}
int main()
{
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++)
	{
		scanf("%lf%lf",&a[i],&b[i]);
		c[i]=(1.00*b[i])/(a[i]*1.00);
	}
	sort(c+1,c+1+n,cmp);
	for(int i=1;i<=n;i++)
	{
		if(a[i]<=m)
		{
			ans+=b[i];
			m-=a[i];
		}
		else
		{
			ans+=c[i]*m;
			break;
		}
	}
	printf("%.2lf",ans);
	return 0;
}