#include<algorithm>
#include <iostream>
#include<iomanip>
using namespace std;
double weight[105], jiazhi[105];
double pingjun[105],weizhi[105];
int n, t;

int main()
{
    cin >> n >> t;
    for (int i = 0; i < n; i++)
    {
        cin >> weight[i] >> jiazhi[i];
        double m = jiazhi[i] / weight[i];
        pingjun[i] = m;
        weizhi[i] = m;
    }
    sort(pingjun, pingjun + n);
    double  xian=0;
    double sum = 0;
    for (int i=1; (t-xian)>0.0000001,i<n;i++)
    {
        int k=0;
        for (int j= 0; j < n; j++)
        {
            if (pingjun[n-i] == weizhi[j])
                k = j;
        }
        if (weight[k] <= (t - xian))
        {
            xian = xian + weight[k];
            sum = sum + jiazhi[k];
        }
        else
        {
            sum = sum + pingjun[n - i] * (t - xian);
        }
    }
    cout <<fixed<<setprecision(2)<< sum;
    return 0;
}