#include <iostream>
#include <vector>
#include <tuple>
#include <climits>
#include <algorithm>
using namespace std;
int main(){
  int n;
  double x,y,x0,y0,xi,yi,wi,T,TC,TA;
  TA=0;
  cin>>x0>>y0;
  x=x0;
  y=y0;
  cin>>n;
  vector<tuple<double,double,double>> v;
  int ws=0;
  for(int i=0; i<n; ++i){
    cin>>xi>>yi>>wi;
    tuple<double,double,double> t;
    t=make_tuple(wi,xi,yi);
    v.push_back(t);
    ws+=wi;
  }
  double d;
  int p;
  double dx,dy,dd;
  while(1){
  d=SHRT_MAX;
  if(v.size()==0){
    dx=x-x0;
    dy=y-y0;
    dd=abs(dx)+abs(dy);
    T=(ws+100);
    T/=120;
    TC=dd*T;
    TA+=TC;
    break;
  }
  for(int i=0; i<v.size(); ++i){
    double& xt=get<1>(v[i]);
    double& yt=get<2>(v[i]);
    dx=xt-x;
    dy=yt-y;
    dd=abs(dx)+abs(dy);
    if(dd<d){
      d=dd;
      p=i;
    }
  }
  double& wt=get<0>(v[p]);
  double& xt=get<1>(v[p]);
  double& yt=get<2>(v[p]);
  dx=xt-x;
  dy=yt-y;
  dd=abs(dx)+abs(dy);
  T=(ws+100);
  T/=120;
  TC=dd*T;
  x=xt;
  y=yt;
  TA+=wt;
  TA+=TC;
  ws-=wt;
  v.erase(v.begin()+p);
  }
  cout<<TA<<endl;
  return 0;
}