#include<bits/stdc++.h>
using namespace std;
struct coin{
    int m,v;
}a[110];
int n,t,c,i;
bool cmp(coin a,coin b){
    return a.v*b.m>a.m*b.v;
}
float ans=0;
int main(){
    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(i=0;i<n;i++){
        if(a[i].m>c)
            break;
        c-=a[i].m;
        ans+=a[i].v;
    }
    if(i<n)
        ans+=1.0*c/a[i].m*a[i].v;
    printf("%.2lf",ans);
    return 0;
}