#include <iostream>
#include <algorithm>

using namespace std;

const int N = 15;
double dp[N][1 << N];

double x[N], y[N], w[N];

const double INF = 1e18;
int n;

double dist(int i, int j){
	return abs(x[i] - x[j]) + abs(y[i] - y[j]);
}

double calc(int i, int j, double w){
	return dist(i, j) * (w + 100) / 120;
}

double rec(int v, int vis){
	if (!v && vis) return vis + 1 == 1 << n ? 0 : INF;
	double &res = dp[v][vis];
	if (res >= -.5) return res;

	double wt = 0;
	for (int i = 0; i < n; ++i) if (~vis >> i & 1) wt += w[i];

	res = INF;
	for (int i = 0; i < n; ++i){
		if (vis >> i & 1) continue;
		res = min(res, rec(i, vis | (1 << i)) + calc(v, i, wt) + w[i]);
	}
	return res;
}


int main(){
	cout.setf(ios::fixed);
	cout.precision(100);

	cin >> x[0] >> y[0] >> n;
	++n;
	for (int i = 1; i < n; ++i) cin >> x[i] >> y[i] >> w[i];
	for (int i = 0; i < 1 << N; ++i) for (int j = 0; j < N; ++j) dp[j][i] = -1;

	cout << rec(0, 0) << endl;
}