#include <bits/stdc++.h>
using namespace std;
struct zhai{
	int zhong;
	double jia;
}a[110];
bool cmp(zhai x,zhai y){
	return x.jia>y.jia;
}
int main(){
	int n,t;
	double q[110]={},sum=0;
	cin>>n>>t;
	for(int i=1;i<=n;i++){
		cin>>a[i].zhong>>q[i];
		a[i].jia=q[i]/a[i].zhong;
	}
	for(int i=1;i<=n;i++){
        if(t>=a[i].zhong){
            sum+=q[i];
            t-=a[i].zhong;
        }
        else{
            sum+=t*a[i].jia;
            printf("%.2lf",sum);
            return 0;
        }
    }
	return 0;
}