import java.util.Arrays;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sn = new Scanner(System.in);
        int n =sn.nextInt();
        double t =sn.nextDouble();
        int arrs[][] = new int[n][2];
        for (int i=0;i<n;i++){
            arrs[i][0] = sn.nextInt();
            arrs[i][1] = sn.nextInt();
        }
        Arrays.sort(arrs,(a,b)->(b[1]/b[0])-(a[1]/a[0]));
        /*
        for(int i=0;i<n;i++){
            System.out.println(Arrays.toString(arrs[i]));
        }
         */
        double sum=0;
        for (int i=0;i<n&&t>0;i++){
            if (arrs[i][0]<=t){
                t-=arrs[i][0];
                sum+=arrs[i][1];
            }else {
                double d=t/(double) arrs[i][0];
                sum+=d*arrs[i][1];
                t=0;
            }
        }
        System.out.printf("%.2f",sum);
    }
}