#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#include <unordered_map>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) __typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii; typedef long long ll;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }

int main() {
	int N;
	int X0, Y0;
	scanf("%d%d", &X0, &Y0);
	scanf("%d", &N);
	vector<int> X(N+1), Y(N+1);
	vector<double> W(N);
	rep(i, N)
		scanf("%d%d%lf", &X[i], &Y[i], &W[i]);
	X[N] = X0, Y[N] = Y0;
	vector<double> weights(1 << N);
	rep(i, 1 << N) {
		double w = 0;
		rep(j, N) if(i >> j & 1) w += W[j];
		weights[i] = w;
	}
	double total = weights[(1 << N)-1];
	vector<vector<int> > dists(N+1, vector<int>(N+1));
	rer(i, 0, N) rer(j, 0, N)
		dists[i][j] = abs(X[i] - X[j]) + abs(Y[i] - Y[j]);
	vector<vector<double> > dp(1 << N, vector<double>(N, 1e99));
	rep(i, N)
		dp[((1 << N) - 1) & ~(1 << i)][i] = (total + 100) / 120 * dists[N][i];
	for(int S = (1 << N)-1; S >= 0; -- S) rep(i, N) {
		double x = dp[S][i];
		if(x == 1e99) continue;
//		cerr << S << ", " << i << ": " << x << endl;
		rep(j, N) if(S >> j & 1)
			amin(dp[S & ~(1 << j)][j], x + (weights[S] + 100) / 120 * dists[i][j]);
	}
	double ans = 1e99;
	rep(i, N)
		amin(ans, dp[0][i] + 100 / 120. * dists[i][N]);
	ans += total;
	printf("%.10f\n", ans);
	return 0;
}