#include<iostream>
#include<algorithm>
using namespace std;
typedef struct{
	double w,v;
    double z;
	
}s;
int cmp(s a,s b){
	return a.z>b.z;
}
int main(){
     s a[10000]={0};
    int n,t,i;
	 double sum=0.00;
      cin>>n>>t;
	for(i=1;i<=n;i++){
		cin>>a[i].w>>a[i].v;
		a[i].z=a[i].v/a[i].w;
	}
	sort (a,a+n,cmp);
	for(i=1;i<=n;i++){
		if(a[i].w<=t){
		
		sum+=a[i].v;
		t-=a[i].w;
	}
		if(a[i].w>t){
			sum+=t*a[i].z;
        break;
		}
		
	}
	cout<<sum;
	return 0;
}