#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-8;
const int MOD = 1000000007;
// const int MOD = 998244353;
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
const int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  vector<int> x(1), y(1);
  int n;
  cin >> x[0] >> y[0] >> n;
  ++n;
  x.resize(n);
  y.resize(n);
  vector<double> w(n, 0);
  FOR(i, 1, n) cin >> x[i] >> y[i] >> w[i];
  double sum = accumulate(ALL(w), 0.0);
  vector<vector<double> > dp(1 << n, vector<double>(n, LINF));
  dp[1][0] = 0;
  FOR(i, 1, 1 << n) {
    double W = sum;
    REP(j, n) {
      if (i >> j & 1) W -= w[j];
    }
    REP(j, n) {
      if (!(i >> j & 1)) continue;
      REP(k, n) {
        if (i >> k & 1) continue;
        int dist = abs(x[k] - x[j]) + abs(y[k] - y[j]);
        chmin(dp[i | (1 << k)][k], dp[i][j] + (W + 100) / 120 * dist + w[k]);
      }
    }
  }
  double ans = LINF;
  FOR(i, 1, n) chmin(ans, dp[(1 << n) - 1][i] + (abs(x[i] - x[0]) + abs(y[i] - y[0])) * 5.0 / 6);
  cout << ans << '\n';
  return 0;
}