#include <iostream>
#include <algorithm>
#include <cmath>
#include <cstdio>

using namespace std;
int n;
double G[15][15];
double W[15];
double wsum;
double x[15],y[15];
double state[15][1<<15];

double dfs(int node,int bit,double w){
  if(bit==1) return G[0][node]*(wsum+100)/120.0;
  if(state[node][bit]) return state[node][bit];
  double ret = 1<<30;
  for(int j=1;j<=n;++j){
    if((bit>>j)&1){
      ret = min(ret,dfs(j,bit&(~(1<<j)),w+W[j])+W[j]+G[j][node]*(w+100)/120.0);
    }
  }
  return state[node][bit] = ret;
}

void input(){
  cin >> x[0] >> y[0];
  W[0] = 0;
  cin >> n;
  for(int i=1;i<=n;++i){
    cin >> x[i] >> y[i] >> W[i];
  }
}

void init(){
  for(int i=0;i<=n;++i){
    for(int j=i+1;j<=n;++j){
      G[i][j] = G[j][i] = abs(x[i]-x[j])+abs(y[i]-y[j]);
    }
  }
  for(int i=1;i<=n;++i) wsum+=W[i];
}

int main(){
  input();
  init();
  printf("%.10lf\n",dfs(0,(1<<(n+1))-1,0));
  return 0;
}