int n, m, x[14], y[14], p, q;
double w[13], dp[1 << 13][13];
double dist(int i, int j) {
	return abs(x[i] - x[j]) + abs(y[i] - y[j]);
}
double calc(int i, int j, double weight) {
	return (weight + 100.0) / 120.0 * dist(i, j);
}
{
	rd(p, q, n, (x, y, w)(n));
	x[n] = p;
	y[n] = q;
	m = 1 << n;
	rep(i, m) rep(j, n) dp[i][j] = ll_inf;
	rep(v, n) dp[m - 1][v] = dist(v, n) * 5.0 / 6;
	rrep(s, m - 1) {
		double k = 0;
		rep(v, n) if (!(s & 1 << v)) k += w[v];
		k = (k + 100) / 120;
		rep(v, n) rep(u, n) {
			if (!(s & 1 << u)) {
				dp[s][v] = min(dp[s][v], dp[s | 1 << u][u] + dist(v, u) * k + w[u]);
			}
		}
	}
	double ans = ll_inf, k = (sum(w(n)) + 100) / 120;
	rep(i, n) ans = min(ans, dp[0][i] + k * dist(i, n));
	wt(ans);
}