#include<bits/stdc++.h>
#define inf 0x3f3f3f3f
#define maxn 1050
using namespace std;
int n,t;
double d[maxn],s[maxn];
double ans=-1;
bool check(double x){
	double ret=0;
	for(int i=1;i<=n;i++) ret+=d[i]/(s[i]+x);
	return ret>=t;
}
int main(){
//	freopen("input.txt","r",stdin);
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin>>n>>t;
	int Min=inf;
	for(int i=1;i<=n;i++){
		cin>>d[i]>>s[i];
		Min=min(Min,(int)s[i]);
	}
	Min=-Min;
	double l=(double)Min,r=1000000000.0,mid=0.0;
	while(l-r<=1e-7){
		mid=(l+r)/2.0;
		if(check(mid)){
			ans=mid;
			l=mid+1e-7;
		}
		else r=mid-(1e-7);
	}
	printf("%.6lf\n",ans);
	return 0;
}

#include<bits/stdc++.h>
int g[30][30];
using namespace std;
int main(){
//	freopen("input.txt","r",stdin);
	ios::sync_with_stdio(false);
	cin.tie(0);
	int n,m;
	cin>>m>>n;
	memset(g,0,sizeof(g));
	for(int i=1;i<=m;i++){
		char a,b;
		cin>>a>>b;
		g[a-'a'][b-'a']=1;
	}
	for(int i=0;i<26;i++){
		for(int j=0;j<26;j++){
			if(g[i][j]==1){
				for(int k=0;k<26;k++){
					if(g[k][i]==1) g[k][j]=1;
				}
			}
		}
	}
	for(int i=1;i<=n;i++){
		string s1,s2;
		cin>>s1>>s2;
		if(s1.length()!=s2.length()){
			cout<<"no"<<endl;
			continue;
		}
		int flag=0;
		for(int j=0;j<s1.length();j++){
			if((s1[j]==s2[j])||(s1[j]!=s2[j]&&g[s1[j]-'a'][s2[j]-'a']==1)) flag++;
		}
		if(flag==s1.length()) cout<<"yes"<<endl;
		else cout<<"no"<<endl;
	}
	return 0;
}

#include<bits/stdc++.h>
#define LL long long
#define N 333
#define n 257
const LL inf =1e18; 
using namespace std;
LL f[N][N],cost[N][N];
int a[N];
int main(){
//	freopen("input.txt","r",stdin);
	ios::sync_with_stdio(false);
	cin.tie(0);
	int d,p;
	cin>>d>>p;
	p++;
	for(int i=0;i<d;i++){
		int x,y;
		cin>>x>>y;
		a[x+1]=y;
	}
	for(int i=0;i<n;i++){
		for(int j=i+1;j<=n;j++){
			cost[i][j]=0;
			for(int k=i+1;k<=j-1;k++){
				int dist=min(i==0?n:k-i,j==n?n:j-k);
				cost[i][j]+=a[k]*1LL*dist*dist;
			}
		}
	}
	for(int i=0;i<=n;i++){
		for(int j=0;j<=p;j++){
			f[i][j]=inf;
		}
	}
	f[0][0]=0;
	for(int i=0;i<n;i++){
		for(int j=0;j<p;j++){
			if(f[i][j]==inf) continue;
			for(int k=i+1;k<=n;k++){
				f[k][j+1]=min(f[k][j+1],f[i][j]+cost[i][k]);
			}
		}
	}
	cout<<f[n][p]<<endl;
	return 0;
}