import java.util.Arrays;
import java.util.Scanner;

class Main {
	public static void main(String[] args) {
		new Main().run();
	}
	
	void run() {
		Scanner sc=new Scanner(System.in);
		long X0=sc.nextLong();
		long Y0=sc.nextLong();
		int N=sc.nextInt();
		long[] X=new long[N+1];
		long[] Y=new long[N+1];
		double[] W=new double[N+1];
		for(int i=0;i<N;++i) {
			X[i+1]=sc.nextLong();
			Y[i+1]=sc.nextLong();
			W[i+1]=sc.nextDouble();
			X[i+1]-=X0;
			Y[i+1]-=Y0;
		}
		N++;
		double[] sumW=new double[1<<N];
		Arrays.fill(sumW,Arrays.stream(W).sum());
		for(int s=0;s<1<<N;++s) {
			for(int shift=0;shift<N;++shift) {
				if((s>>shift)%2==1)sumW[s]-=W[shift];
			}
		}
		double[][] dp=new double[1<<N][N];
		double INF=Double.MAX_VALUE/3;
		for(int i=0;i<dp.length;++i)
			for(int j=0;j<dp[i].length;++j)
				dp[i][j]=INF;
		dp[1][0]=0;
		for(int s=0;s<(1<<N)-1;++s) {
			for(int cur=0;cur<N;++cur) {
				if((s>>cur)%2==0)continue;
				for(int next=0;next<N;++next) {
					if((s>>next)%2==1)continue;
					int ns=s|1<<next;
					double dist=Math.abs(X[cur]-X[next])+Math.abs(Y[cur]-Y[next]);
					dp[ns][next]=Math.min(dp[ns][next], dp[s][cur]+dist*(sumW[s]+100)/120+W[next]);
				}
			}
		}
		double ans=Double.MAX_VALUE/3;
		for(int i=1;i<N;++i) {
			double dist=Math.abs(X[i])+Math.abs(Y[i]);
			ans=Math.min(ans, dp[(1<<N)-1][i]+dist*100/120);
		}
		System.out.println(ans);
	}
	
	static void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}

}