#include<bits/stdc++.h>
using namespace std;
int n,t;
struct treasure{
    int m,v;
}a[105];
double ans;
bool cmp(const treasure &a,const treasure &b){
    return a.m*b.v>a.v*b.m;
}
int main(){
    cin>>n>>t;
    for(int i=1;i<=n;i++)
        cin>>a[i].m>>a[i].v;
    sort(a+1,a+n+1,cmp);
    for(int i=1;i<=n;i++){
        if(t>a[i].m){
            t-a[i].m;
            ans+=a[i].v*1.0;
        }
        else{
            ans+=a[i].v*1.0/(a[i].m*1.0)*t;
            break;
        }
    }
    printf("%.2lf",ans);
    return 0;
}