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

#define rep(i,j,n) for(int i=j;i<n;++i)
#define all(i) i.begin(),i.end()
#define rall(i) i.rbegin(), i.rend()
#define INF 1e9
#define LINF 1e18
const int mod = 1e9 + 7;

typedef long long i64;
typedef pair<int, int> pi;

template <class T> using vt = vector<T>;
template <class T> using vvt = vector<vector<T>>;

i64 gcd(i64 n, i64 m) {return (m == 0? n : gcd(m, n % m));}
i64 lcd(i64 n, i64 m) {return (n / gcd(n, m) * m);}
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int x0, y0, n;
  cin >> x0 >> y0 >> n;
  vt<int> x(n), y(n);
  vt<double> w(n);
  rep(i, 0, n) cin >> x[i] >> y[i] >> w[i];

  vt<double> t(1 << n);
  rep(bit, 0, (1 << n)) {
    double sum = 0.0;
    rep(i, 0, n) {
      if(bit & (1 << i)) continue;
      sum += w[i];
    }
    t[bit] = (sum + 100) / 120;
  }

  vvt<double> dp(n, vt<double>(1 << n, DBL_MAX));
  rep(i, 0, n) {
    dp[i][(1 << i)] = (abs(x[i] - x0) + abs(y[i] - y0)) * t[0] + w[i];
  }
  rep(bit, 0, (1 << n)) {
    rep(i, 0, n) {
      if(!(bit & (1 << i))) continue;
      rep(j, 0, n) {
        if(bit & (1 << j)) continue;

        dp[j][bit | (1 << j)] = min(dp[j][bit | (1 << j)], dp[i][bit] + (abs(x[j] - x[i]) + abs(y[j] - y[i])) * t[bit] + w[j]);
      }
    }
  }

  double ans = DBL_MAX;
  rep(i, 0, n) {
    ans = min(ans, dp[i][(1 << n) - 1] + (abs(x[i] - x0) + abs(y[i] - y0)) * t[(1 << n) - 1]);
  }
  cout << fixed << setprecision(10) << ans << endl;
}