#include<bits/stdc++.h>
using namespace std;
struct qwq{
	double m,v,z;
}N[110];
int main(){
	int l,a,n,t1,t2=0;
	double zj=0;
	cin>>n>>t1;
	for(int i=0;i<n;i++){
		cin>>N[i].m>>N[i].v;
		N[i].z=N[i].v/N[i].m;
	}
	while(t1>t2){
		for(i=0,l=0;i<n;i++){
			if(N[i].z>l) {
				l=N[i].z;
				a=i;
			}
		}
		if(t1<=t2+N[a].m){
			zj+=(t1-t2)*N[a].z;
			t2+=N[a].m;
		} 
		else {
			zj+=N[a].v;
			t2+=N[a].m;
			N[a].z=0;
		}
	}
	printf("%.2lf",zj);
	return 0;
}

只有样例过了qwq