#include <bits/stdc++.h>
using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)   FOR(i,0,n)
#define ALL(a)     (a).begin(),(a).end()
#define RALL(a)     (a).rbegin(),(a).rend()
#define PRINT(a)   cout << (a) << endl

#define pb push_back
#define eb emplace_back
#define mp make_pair
#define Fi first
#define Se second

#define debug(x) cerr << x << " " << "(L:" << __LINE__ << ")" << '\n';

using ll = long long int;
using P = pair<int,int>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using pii = pair<int, int>;

template <typename T> using PQ = priority_queue<T>;
template <typename T> using minPQ = priority_queue<T, vector<T>, greater<T>>;

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

const int INF = 1001001001;
const ll LINF = 1001001001001001001ll;
const int MOD = 1e9 + 7;

int main(){
  double x0, y0;
  cin >> x0 >> y0;

  int n;
  cin >> n;
  n++;
  int S = 1<<n;
  vector<double> x(n), y(n), w(n);
  x[0]=x0;
  y[0]=y0;
  REP(i,n-1)cin >> x[i+1] >> y[i+1] >> w[i+1];

  const double INF=1e18;

  vector dp(S, vector<double>(n, INF));
  dp[0][0]=0;

  double tot = 0;
  REP(i,n)tot += w[i];

  vector<double> t(S,tot);
  REP(s, S){
    REP(j,n){
      if((s >> j) & 1)t[s] -= w[j];
    }
  }

  vector dist(n, vector<double>(n));
  REP(i,n)REP(j,n){
    dist[i][j] = abs(x[i]-x[j]) + abs((y[i]-y[j]));
  }

  REP(s, S){
    // u -> v
    REP(u, n){
      if(dp[s][u]==INF)continue;

      REP(v, n){
        if( ~s & (1<<v)){
          chmin(dp[s | (1<<v)][v], dp[s][u] + dist[u][v] * ((t[s] + 100)/120) + w[v]);
        }
      }
    }
  }
  // REP(s, S){
  //   // u -> v
  //   REP(u, n){
  //     if(dp[s][u]==INF)continue;
  //     printf("%d %d %.10f\n", s, u, dp[s][u]);
  //   }
  // }
  printf("%.10f\n", dp[S-1][0]);
}