#include<iostream>
#include<algorithm>
using namespace std;
#define FOR(i, a, n) for(int i=a; i<n; i++)
#define RFOR(i, a, n) for(int i=n-1; i>=a; i--)
#define REP(i, n) FOR(i, 0, n)
#define RREP(i, n) FOR(i, 0, n)
#define INF 10000000

double dp[(1 << 14)][14];
int main()
{
	int X[14], Y[14], N;
	double W[14], sumW = 0.0;
	cin >> X[0] >> Y[0] >> N;
	W[0] = 0.0;
	REP(i, N) {
		cin >> X[i + 1] >> Y[i + 1] >> W[i + 1];
		sumW += W[i + 1];
	}
	N++;
	REP(i, 1 << N) REP(j, N) dp[i][j] = INF;

	dp[0][0] = 0;
	REP(mask, 1 << N) {
		REP(i, N) {
			double sw = sumW;
			REP(j, N) if (mask&(1 << j)) sw -= W[j];
			REP(j, N) {
				if (mask&(1 << j)) continue;
				int md = abs(X[j] - X[i]) + abs(Y[j] - Y[i]);
				dp[mask | (1 << j)][j] = min(dp[mask | (1 << j)][j], dp[mask][i] + (md*(sw + 100.0) / 120.0) + W[j]);
			}
		}
	}

	cout << dp[(1 << N) - 1][0] << endl;
	return 0;
}