#include <bits/stdc++.h>

using namespace std;

ifstream fin("energii.in");
ofstream fout("energii.out");

struct ob
{
    int g, v;
};

ob a[1005];
int n, G;

void Citire()
{
    fin >> n >> G;
    for(int i = 1; i <= n; i++)
        fin >> a[i].g >> a[i].v;
}

bool comp(ob A, ob B)
{
    return A.v * B.g < B.v * A.g;
}

void Greedy()
{
    int i;
    sort(a+1, a+n+1, comp);
    double cost = 0;
    for(i = 1; i <= n && G >= a[i].g; i++)
    {
        G -= a[i].g;
        cost += a[i].v;
    }
    fout << cost;
}

int main()
{
    Citire();
    Greedy();
    return 0;
}