#include<bits/stdc++.h>
using namespace std;
struct Node {
	   int m,v;
	   double p;
} gold[2000];
bool cmp(Node a,Node b) {
	return a.p>b.p;
}
int main() {
	double answer;
	int N,T;
	cin>>N>>T;
	for(int i = 0;i<N;i++) cin>>gold[i].m>>gold[i].v;
	for(int i = 0;i<N;i++) gold[i].p=gold[i].v/gold[i].m;
	sort(gold,gold+N,cmp);
	for(int i=0;i<N;i++) {
		if(gold[i].m<T) answer+=gold[i].v,T-=gold[i].m;
		else {
			answer+=T*gold[i].p;
			break;
		}
	}
	printf("%.2lf",answer);
	return 0;
}