#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v; ll w; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int main() {
	int X0, Y0; cin >> X0 >> Y0;
	int N; cin >> N;
	vector<int> X(N + 1), Y(N + 1);
	vector<double> W(N + 1);
	X[0] = X0; Y[0] = Y0;
	for (int i = 1; i <= N; i++)
		cin >> X[i] >> Y[i] >> W[i];
	vector< vector<double> > d(N + 1, vector<double>(N + 1));
	for (int i = 0; i <= N; i++)
		for (int j = 0; j <= N; j++) {
			int dx = X[i] - X[j], dy = Y[i] - Y[j];
			d[i][j] = abs(dx) + abs(dy); //hypot(dx, dy);
		}
	vector< vector<double> > dp(1 << (N + 1), vector<double>(N + 1, DBL_MAX / 2));
	dp[0][0] = 0;
	for (int S = 0; S < (1 << (N + 1)); S++) {
		double w = 0;
		for (int i = 0; i <= N; i++)
			if (!(S & (1 << i)))
				w += W[i];
		for (int i = 0; i <= N; i++)
			for (int j = 0; j <= N; j++) {
				if (S & (1 << j)) continue;
				int T = S | (1 << j);
				dp[T][j] = min(dp[T][j], dp[S][i] + d[i][j] * (w + 100) / 120 + W[j]);
			}
	}
	printf("%.10f\n", dp[(1 << (N + 1)) - 1][0]);
}