#include <bits/stdc++.h>
using namespace std;
int main()
{
	double x, y;
	cin >> x >> y;
	vector<pair<double, double>> V = {{x, y}};
	int N;
	cin >> N;
	vector<double> W(N + 1);
	V.resize(N + 1);
	for (int i = 1; i <= N; i++)
		cin >> V[i].first >> V[i].second >> W[i];

	auto dis = [&](int a, int b)
	{
		return abs(V[a].first - V[b].first) + abs(V[a].second - V[b].second);
	};

	vector<vector<double>> D(1 << (N + 1), vector<double>(N + 1, -1));
	function<double(int, int)> F = [&](int msk, int lst)
	{
		if(D[msk][lst] >= 0) return D[msk][lst];
		double w = 0;
		for (int i = 1; i <= N; i++)
			if (msk & (1 << i))
				w += W[i];
		double t = (w + 100) / 120;
		if (msk == 0)
			return D[msk][lst] = dis(lst, 0) * t;
		double ans = numeric_limits<double>::infinity();
		for (int i = 1; i <= N; i++)
			if (msk & (1 << i))
				ans = min(ans, W[i] + dis(i, lst) * t + F(msk - (1 << i), i));
		return D[msk][lst] = ans;
	};
	cout << fixed << setprecision(12) << F((1 << (N + 1)) - 2, 0) << endl;
}