#include<stdio.h>
#include<algorithm>
#define MAX(x,y) x>y?x:y
using namespace std;
const int MAXN=10010;
struct Node{int v,w;
};
Node res[MAXN];
double cont[MAXN];
int n,k;
int fun(double mid){    for(int i=0;i<n;i++){cont[i]=res[i].v-mid*res[i].w;}sort(cont,cont+n);double sum=0;for(int i=n-1;i>=n-k;i--)sum+=cont[i];    //printf("%lf\n",mid);return sum>=0?1:0;
}
double abs(double x){return x>0?x:-x;
}
double search(double max){    double left=0,right=max,mid;while(right-left>1e-10){mid=(left+right)/2;if(fun(mid))left=mid;else right=mid;}return mid;
}
int main(){while(~scanf("%d%d",&n,&k)){double max=0;for(int i=0;i<n;i++){scanf("%d%d",&res[i].w,&res[i].v);max=MAX(max,res[i].v*1.0/res[i].w);//        }printf("%.2f\n",search(max));}return 0;
}

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cmath>
using namespace std;
const int MAXN=10010;
struct Node{int a,b;
};
Node dt[MAXN];
double d[MAXN];
int n,k;
bool fsgh(double R){double sum=0;for(int i=0;i<n;i++)d[i]=dt[i].a-R*dt[i].b;sort(d,d+n);for(int i=n-1;i>=n-k;i--)sum+=d[i];return sum>0?true:false;
}
double erfen(double l,double r){double mid;while(r-l>1e-6){mid=(l+r)/2;if(fsgh(mid))l=mid;else r=mid;}return mid;
}
int main(){while(scanf("%d%d",&n,&k),n|k){double mx=0;k=n-k;for(int i=0;i<n;i++)scanf("%d",&dt[i].a);for(int i=0;i<n;i++)scanf("%d",&dt[i].b),mx=max(1.0*dt[i].a/dt[i].b,mx);printf("%.0f\n",erfen(0,mx)*100);}return 0;
}

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cmath>
#include<algorithm>
#define mem(x,y) memset(x,y,sizeof(x))
using namespace std;
const int INF=0x3f3f3f3f;
typedef long long LL;
const int MAXN=1010;
double vis[MAXN],low[MAXN];
int N;
double R;
struct Node{double x,y,h;
};
Node dt[MAXN];
double len[MAXN][MAXN],cost[MAXN][MAXN];
double getl(Node a,Node b){double x=b.x-a.x,y=b.y-a.y;return sqrt(x*x+y*y);
}bool prime(){double total;mem(vis,0);for(int i=0;i<N;i++)low[i]=cost[0][i]-R*len[0][i];total=0;vis[0]=1;//    for(int i=0;i<N;i++){double temp=INF;int k;for(int j=0;j<N;j++)if(!vis[j]&&low[j]<temp)temp=low[j],k=j;if(temp==INF)break;total+=temp;vis[k]=1;for(int j=0;j<N;j++)if(!vis[j]&&low[j]>cost[k][j]-R*len[k][j])low[j]=cost[k][j]-R*len[k][j];}//printf("total=%lf R=%lf\n",total,R);if(total>0)return true;else return false;
}
int main(){while(scanf("%d",&N),N){mem(len,INF);mem(cost,INF);double mxl=-INF,mil=INF,mxc=-INF,mic=INF;for(int i=0;i<N;i++)scanf("%lf%lf%lf",&dt[i].x,&dt[i].y,&dt[i].h);for(int i=0;i<N;i++){for(int j=i+1;j<N;j++){len[j][i]=len[i][j]=getl(dt[i],dt[j]);cost[j][i]=cost[i][j]=abs(dt[i].h-dt[j].h);mxl=max(mxl,len[i][j]);mxc=max(mxc,cost[i][j]);mil=min(mil,len[i][j]);mic=min(mic,cost[i][j]);}}//printf("%lf %lf %lf %lf\n",mil,mic,mxl,mxc);double l=mic/mxl,r=mxc/mil;        //    printf("%lf %lf\n",l,r);while(r-l>1e-4){R=(l+r)/2;if(prime())l=R;else r=R;}printf("%.3f\n",l);}return 0;
}

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<queue>
#define mem(x,y) memset(x,y,sizeof(x))
using namespace std;
const int INF=10000000000000;
typedef long long LL;
const int MAXN=1010;
const int MAXM=100010;
/*struct Node{int u,v;double t;
};
Node dt[MAXM];*/
struct Edge{int from,to,next,t;
};
Edge edg[MAXM];
int head[MAXM];
int edgnum;
void add(int u,int v,int t){Edge E={u,v,head[u],t};edg[edgnum]=E;head[u]=edgnum++;
}
int L,P;
double hp[MAXN],dis[MAXN];
int usd[MAXN],vis[MAXN];
/*void add(int u,int v,double t){Node E={u,v,t};dt[edgnum++]=E;
}*/
//double R;
/*bool Bellman(){mem(dis,INF);mem(usd,0);dis[1]=0;while(1){int temp=0;for(int j=0;j<edgnum;j++){int u=dt[j].u,v=dt[j].v;double t=dt[j].t;//dis[v]=min(dis[v],dis[u]+R*t-hp[u]);//应该是R*t-hp[u]; if(dis[v]>dis[u]+R*t-hp[u])usd[v]++,dis[v]=dis[u]+R*t-hp[u],temp=1;if(usd[v]>L)return false;}if(!temp)return true;}
}*/
bool SPFA(double R){queue<int>dl;while(!dl.empty())dl.pop();for(int i=1;i<=L;i++){dis[i]=INF;vis[i]=0;usd[i]=0;}dl.push(1);vis[1]=1;usd[1]++;dis[1]=0;while(!dl.empty()){int u=dl.front();dl.pop();vis[u]=0;for(int i=head[u];i!=-1;i=edg[i].next){int v=edg[i].to,t=edg[i].t;if(dis[v]>dis[u]+R*t-hp[u]){dis[v]=dis[u]+R*t-hp[u];if(!vis[v]){vis[v]=1;usd[v]++;dl.push(v);//  printf("%d\n",usd[v]);if(usd[v]>=L)return false;}}}}return true;
}
int main(){int a,b;int c;while(~scanf("%d%d",&L,&P)){edgnum=0;double mih=INF,mxh=-INF;int mit=INF,mxt=-INF;mem(head,-1);for(int i=1;i<=L;i++){scanf("%lf",hp+i);mih=min(mih,hp[i]);mxh=max(mxh,hp[i]);}while(P--){scanf("%d%d%d",&a,&b,&c);add(a,b,c);mit=min(mit,c);mxt=max(mxt,c);}double l=mih/mxt,r=mxh/mit;//  printf("%f %f\n",l,r);double R;while(r-l>=0.001){R=(l+r)/2;if(SPFA(R))r=R;else l=R;}printf("%.2f\n",l);}return 0;
}