#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<algorithm>
using namespace std;
int n,t;
struct node{
	int b,c;
	double value;
}a[100001];
bool cmp(node a,node b)
{
	return a.value>b.value;
}
int main()
{
	cin>>n>>t;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i].b>>a[i].c;
		a[i].value=a[i].c*1.0/a[i].b;
	}
	double ans=0,s=0;
	for(int i=1;i<=n;i++)
	{
		if(s+a[i].b>t)
		{
			ans+=(t-s)*a[i].value;
			break;
		}
		ans+=a[i].c;
		s+=a[i].b;
	}
	printf("%.2lf",ans);
}