#include<iostream>
#include<climits>
#include<set>
#include<map>
#include<vector>
#include<string>
#include<algorithm>
#include<math.h>
#include<queue>
#include<deque>
#include<stack>
#include<assert.h>
#include<numeric>
#include<bitset>

#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#define all(x) (x).begin(),(x).end()

typedef long long ll;
using namespace std;
const int inf = INT_MAX / 2;
const ll infl = 1LL << 62;
const double PI = 2 * acos(0.0);
template<class T>bool chmax(T& a, const T& b) { if (a < b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; }
ll gcd(ll a, ll b) { return a ? gcd(b % a, a) : b; }

int N;
double X[20], Y[20], W[20];
double dp[10000][20];
int main() {
	cin >> X[0] >> Y[0];
	cin >> N;
	for (int i = 1; i <= N; i++) cin >> X[i] >> Y[i] >> W[i];
	for (int i = 0; i < 1 << (N + 1); i++) for (int j = 0; j < N + 1; j++) dp[i][j] = infl;
	dp[0][0] = 0;

	for (int msk = 0; msk < 1 << (N + 1); msk++) {
		double w = 0;
		for (int i = 0; i < N + 1; i++) if (!(msk & 1 << i)) w += W[i];
		double T = (w + 100) / 120;

		for (int i = 0; i < N + 1; i++) {
			for (int j = 0; j < N + 1; j++) {
				if (msk & 1 << j) continue;
				double dis = abs(X[j] - X[i]) + abs(Y[j] - Y[i]);
				chmin(dp[msk + (1 << j)][j], dp[msk][i] + dis * T + W[i]);
			}
		}
	}
	
	cout << dp[(1 << (N + 1)) - 1][0] << endl;
}