#include <bits/stdc++.h>

using namespace std;

const double INF = 1e10;

int x[15], y[15];
double w[15];
double dp[1 << 13][13];

double dist(int x1, int y1, int x2, int y2) {
	return abs(x1 - x2) + abs(y1 - y2);
}

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int x0, y0, n;
	cin >> x0 >> y0 >> n;
	double wsum = 0.0;
	for (int i = 0; i < n; i++) {
		cin >> x[i] >> y[i] >> w[i];
		wsum += w[i];
	}

	for (int i = 0; i < (1 << n); i++) {
		for (int j = 0; j < n; j++) {
			dp[i][j] = INF;
		}
	}

	for (int i = 0; i < n; i++) {
		double tmp = dist(x[i], y[i], x0, y0) * (wsum + 100) / 120 + w[i];
		dp[1 << i][i] = tmp;
	}

	for (int i = 1; i < (1 << n) - 1; i++) {
		wsum = 0.0;
		for (int j = 0; j < n; j++) {
			if (i & (1 << j)) continue;
			wsum += w[j];
		}
		for (int j = 0; j < n; j++) {
			if (i & (1 << j)) {
				for (int k = 0; k < n; k++) {
					if (i & (1 << k)) continue;
					double tmp = dist(x[j], y[j], x[k], y[k]) * (wsum + 100) / 120 + w[k];
					dp[i | (1 << k)][k] = min(dp[i | (1 << k)][k], dp[i][j] + tmp);
				}
			}
		}
	}
	double ans = INF;
	for (int i = 0; i < n; i++) {
		ans = min(ans, dp[(1 << n) - 1][i] + dist(x0, y0, x[i], y[i]) * 100 / 120);
	}
	cout << fixed << setprecision(10) << ans << endl;
	return 0;
}