#include<iostream>
#include<bits/stdc++.h>
using namespace std;
struct b{
	int m;
	int v;
	double xjb;
}bb[1001];
bool cmp(b a1,b b1){
	return a1.xjb>b1.xjb;
}
int main(){
int n,t;
cin>>n>>t;
for(int i=0;i<n;i++){
	cin>>bb[i].m>>bb[i].v;
	bb[i].xjb=1.0*bb[i].v/bb[i].m;
} 
sort(bb,bb+n,cmp);
int k=0;
double cnt=0;
while(t>0&&k<n){
	if(t>=bb[k].m){
		t-=bb[k].m;
		cnt+=bb[k].v;
	}else{
		break;
	}
	k++;
}
cnt+=1.*t/bb[k].m*bb[k].v;
printf("%.2lf",cnt);
	return 0;
}