#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)




int X0, Y0;
int N;
int X[13], Y[13];
double W[13];
//-----------------------------------------------------------------
const double INF = 1e12;
double dp[1 << 13][13];
int main() {
	cin >> X0 >> Y0 >> N;
	rep(i, 0, N) cin >> X[i] >> Y[i] >> W[i];

	rep(i, 0, 1 << N) rep(j, 0, N) dp[i][j] = INF;

	// dp[0][?]からの遷移だけ最初にやっとく
	rep(i, 0, N) {
		int d = abs(X0 - X[i]) + abs(Y0 - Y[i]);
		double v = 100.0 / 120.0;
		dp[1 << i][i] = v * d + W[i];
	}

	rep(ma, 1, 1 << N) rep(last, 0, N) {
		double w = 0;
		rep(i, 0, N) if (ma & (1 << i)) w += W[i];
		double v = (w + 100.0) / 120.0;

		rep(i, 0, N) if (!(ma & (1 << i))) {
			int d = abs(X[last] - X[i]) + abs(Y[last] - Y[i]);
			int mama = ma + (1 << i);
			dp[mama][i] = min(dp[mama][i], dp[ma][last] + v * d + W[i]);
		}
	}

	double ans = INF;
	double w = 0;
	rep(i, 0, N) w += W[i];
	double v = (w + 100.0) / 120.0;
	rep(i, 0, N) {
		int d = abs(X0 - X[i]) + abs(Y0 - Y[i]);
		ans = min(ans, dp[(1 << N) - 1][i] + v * d);
	}
	printf("%.10f\n", ans);
}