#include<stdio.h>
int main()
{
	int m;
	double n;
	scanf("%d %lf",&m,&n);
	double a[m],b[m],c[m];
	for(int i=0;i<m;i++){
		scanf("%lf %lf",&a[i],&b[i]);
	}
	for(int j=0;j<m;j++){
		c[j]=b[j]/a[j];
	}
	for(int i=0;i<m;i++){
		for(int j=0;j<m-i;j++){
			if(c[i+1]>c[i]){
				a[i+1]=a[i]+a[i+1];
				a[i]=a[i+1]-a[i];
				a[i+1]=a[i+1]-a[i];
				b[i+1]=b[i]+b[i+1];
				b[i]=b[i+1]-b[i];
				b[i+1]=b[i+1]-b[i];
				c[i+1]=c[i]+c[i+1];
				c[i]=c[i+1]-c[i];
				c[i+1]=c[i+1]-c[i];
			}
		}
	}double sum,num;
	for(int i=0;i<m;i++){
		sum=sum+b[i];
		num=num+a[i];
		if(num>n){
			sum=sum-b[i];
			num=num-a[i];
			sum=c[i]*(n-num)+sum;
			break;
		}
	}
	printf("%.2lf",sum);
	return 0;
}