#include <bits/stdc++.h>
using namespace std;
typedef long double ld;
ld dp[1<<14][14];
ld weight[1<<14];
int main(){
	int sx,sy;	cin>>sx>>sy;
	int n;	cin>>n;
	vector<int> x(n),y(n);
	vector<double> w(n);
	for(int i=0;i<n;i++)	cin>>x[i]>>y[i]>>w[i];
	x.insert(x.begin(),sx);	y.insert(y.begin(),sy);	w.insert(w.begin(),0.0);
	n++;
	double sw=0;
	for(int i=0;i<n;i++)	sw+=w[i];
	for(int i=0;i<(1<<n);i++){
		for(int j=0;j<n;j++){
			if((i>>j)%2)	weight[i]+=w[j];
		}
		weight[i]=sw-weight[i];
	}
	for(int i=0;i<(1<<n);i++){
		for(int j=0;j<n;j++)	dp[i][j]=(1<<30);
	}
	dp[0][0]=0;
	for(int i=0;i<(1<<n);i++){
		for(int j=0;j<n;j++){
			if(dp[i][j]==(1<<30))	continue;
			for(int k=0;k<n;k++){
				int next=(i|(1<<k));
				dp[next][k]=min(dp[next][k],dp[i][j]+(ld)(abs(x[j]-x[k])+abs(y[j]-y[k]))*(weight[i]+100)/120+w[k]);
			}
		}
	}
	printf("%.15lf\n",(double)dp[(1<<n)-1][0]);
	return 0;
}