#include<iostream>
#include<cstdio>
#include<cmath>
#define inf 0x7fffffff
using namespace std;
inline int read(){
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
return x*f;
}
struct point{
double x,y,v;
}p[1001];
int n;
double xx,yy,ans,t;
inline double dis(double x,double y,point p){
return sqrt((p.x-x)*(p.x-x)+(p.y-y)*(p.y-y));
}
inline doubl......
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