#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000000000000000

int main(){
	
	vector<double> x(1),y(1),w(1);
	cin>>x[0]>>y[0];
	w[0] = 0.0;
	int n;
	cin>>n;
	
	x.resize(n+1),y.resize(n+1),w.resize(n+1);
	double S = 0.0;
	rep(i,n){
		cin>>x[i+1]>>y[i+1]>>w[i+1];
		S += w[i+1];
	}
	n++;
	vector dp(1<<n,vector<double>(n,1e30));
	dp[0][0] = 0.0;
	
	rep(i,1<<n){
		rep(j,n){
			if(dp[i][j]>1e20)continue;
			double W = S;
			rep(k,n){
				if((i>>k)&1)W -= w[k];
			}
			rep(k,n){
				if((i>>k)&1)continue;
				int ni = i | (1<<k);
				int nj = k;
				double nv = dp[i][j];
				nv += (W+100.0)/120.0 * (abs(x[k]-x[j]) + abs(y[k]-y[j]));
				dp[ni][nj] = min(dp[ni][nj],nv);
			}
		}
	}
	
	double ans = dp.back()[0];
	ans += S;
	
	cout<<fixed<<setprecision(10)<<ans<<endl;
	
	return 0;
}