#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 X[14], Y[14];
double W[14];

int main() {
	cin >> X[0] >> Y[0];
	int N; cin >> N; N++;
	for (int i = 1; i < N; i++)
		cin >> X[i] >> Y[i] >> W[i];
	vector< vector<double> > dp(1 << N, vector<double>(N, DBL_MAX));
	dp[0][0] = 0;
	for (int S = 0; S < (1 << N); 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++) {
				double l = abs(X[i] - X[j]) + abs(Y[i] - Y[j]);
				double t = l * (w + 100) / 120 + W[j];
				dp[S | (1 << j)][j] = min(dp[S | (1 << j)][j], dp[S][i] + t);
			}
	}
	printf("%.10f\n", dp[(1 << N) - 1][0]);
}