codeforces 706A A. Beru-taxi(水题)

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <bits/stdc++.h>
#include <stack>
#include <map>
 
using namespace std;
 
#define For(i,j,n) for(int i=j;i<=n;i++)
#define mst(ss,b) memset(ss,b,sizeof(ss));
 
typedef  long long LL;
 
template<class T> void read(T&num) {
    char CH; bool F=false;
    for(CH=getchar();CH<‘0‘||CH>‘9‘;F= CH==‘-‘,CH=getchar());
    for(num=0;CH>=‘0‘&&CH<=‘9‘;num=num*10+CH-‘0‘,CH=getchar());
    F && (num=-num);
}
int stk[70], tp;
template<class T> inline void print(T p) {
    if(!p) { puts("0"); return; }
    while(p) stk[++ tp] = p%10, p/=10;
    while(tp) putchar(stk[tp--] + ‘0‘);
    putchar(‘\n‘);
}
 
const LL mod=1e9+7;
const double PI=acos(-1.0);
const int inf=1e18;
const int N=1e5+10;
const int maxn=5e3+4;
const double eps=1e-12;

int n;
double a,b,x[maxn],y[maxn];
double getdis(double fx,double fy,double fa,double fb)
{
    return sqrt((fx-fa)*(fx-fa)+(fb-fy)*(fb-fy));
}
int main()
{
    scanf("%lf%lf",&a,&b);
   read(n);
   double ans=inf,v;
   For(i,1,n)
   {
        scanf("%lf%lf%lf",&x[i],&y[i],&v);
        ans=min(ans,getdis(a,b,x[i],y[i])/v);
   }
   printf("%.10lf\n",ans);
    return 0;
}