【模拟】Codeforces 706A Beru-taxi

//
//by coolxxx
//
#include<iostream>
#include<algorithm>
#include<string>
#include<iomanip>
#include<memory.h>
#include<time.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
//#include<stdbool.h>
#include<math.h>
#define min(a,b) ((a)<(b)?(a):(b))
#define max(a,b) ((a)>(b)?(a):(b))
#define abs(a) ((a)>0?(a):(-(a)))
#define lowbit(a) (a&(-a))
#define sqr(a) ((a)*(a))
#define swap(a,b) ((a)^=(b),(b)^=(a),(a)^=(b))
#define eps (1e-8)
#define J 10000000
#define MAX 0x7f7f7f7f
#define PI 3.1415926535897
#define N 4
using namespace std;
typedef long long LL;
int cas,cass;
int n,m,lll,ans;
int sx,sy;
double t,s;
int main()
{
#ifndef ONLINE_JUDGE
//    freopen("1.txt","r",stdin);
//    freopen("2.txt","w",stdout);
#endif
int i,j,x,y,v;
//    for(scanf("%d",&cas);cas;cas--)
//    for(scanf("%d",&cas),cass=1;cass<=cas;cass++)
//    while(~scanf("%s",s))
while(~scanf("%d%d",&sx,&sy))
{
t=MAX;
scanf("%d",&n);
for(i=1;i<=n;i++)
{
scanf("%d%d%d",&x,&y,&v);
s=(double)sqrt(sqr(x-sx)+sqr(y-sy))/v;
t=min(t,s);
}
printf("%lf\n",t);
}
return 0;
}
/*
//

//
*/