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

template <typename T, typename U> bool cmin(T &a, U b) { return a > b && (a = b, true); }
template <typename T, typename U> bool cmax(T &a, U b) { return a < b && (a = b, true); }

signed main() {
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);

  int X, Y, N;
  cin >> X >> Y >> N, N++;
  vector<tuple<int, int, double>> V(N);
  V.at(0) = {X, Y, 0};
  for (int i = 1; i < N; i++) {
    int x, y;
    double w;
    cin >> x >> y >> w;
    V.at(i) = {x, y, w};
  }

  vector<vector<int>> dist(N, vector<int>(N));
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < N; j++) {
      auto [a, b, c] = V.at(i);
      auto [d, e, f] = V.at(j);
      dist.at(i).at(j) = abs(a - d) + abs(b - e);
    }
  }

  vector<double> weight(1 << N);
  for (int bit = 0; bit < 1 << N; bit++) {
    double tmp = 0;
    for (int i = 0; i < N; i++) {
      if (bit >> i & 1) {
        auto [a, b, c] = V.at(i);
        tmp += c;
      }
    }
    weight.at(bit) = tmp;
  }

  vector<vector<double>> DP(1 << N, vector<double>(N, DBL_MAX));
  DP.at(1).at(0) = 0;
  for (int bit = 0; bit < 1 << N; bit++) {
    for (int from = 0; from < N; from++) {
      if (DP.at(bit).at(from) == DBL_MAX) continue;
      for (int to = 0; to < N; to++) {
        double cost = dist.at(from).at(to) * ((weight.at(bit) + 100) / 120);
        cmin(DP.at(bit | 1 << to).at(to), DP.at(bit).at(from) + cost);
      }
    }
  }

  double ans = DP.at((1 << N) - 1).at(0);
  for (auto [a, b, c] : V) ans += c;
  cout << fixed << setprecision(7) << ans << "\n";  
}