#include <bits/stdc++.h>

int main() {
	
	int X0,Y0;
	std::cin >> X0 >> Y0;
	int N;
	std::cin >> N;
	std::vector<int> X(N);
	std::vector<int> Y(N);
	std::vector<double> W(N);
	for(int i=0;i<N;++i)
		std::cin >> X[i] >> Y[i] >> W[i];
	int n=1<<N;
	std::vector<std::vector<double>> dp(n,std::vector<double>(N,DBL_MAX));
	auto calc = [&](int x, int y){
		return std::abs(x)+std::abs(y);
	};
	double sumW = std::accumulate(begin(W),end(W),0.0);
	for(int i=0;i<N;++i)
		dp[0][i] = (sumW+100)/120*calc(X0-X[i],Y0-Y[i]);
	for(int x=0;x<n;++x){
		double SW = 0;
		//積んでいる荷物の重さ
		for(int i=0;i<N;++i)
			if(!(x&(1<<i)))SW += W[i];
		for(int i=0;i<N;++i){
			if(x&(1<<i))continue;
			for(int j=0;j<N;++j){
				if(dp[x][j]==DBL_MAX)continue;
				double T = (SW+100)/120*calc(X[j]-X[i],Y[j]-Y[i]);
				int v=x|(1<<i);
				dp[v][i]=std::min(dp[v][i],dp[x][j]+T);
			}
		}
	}
	double ans = DBL_MAX;
	for(int i=0;i<N;++i){
		ans = std::min(ans,dp[n-1][i]+100/120.0*calc(X0-X[i],Y0-Y[i]));
	}
	ans += sumW;
	std::cout << std::fixed << std::setprecision(8) << ans << std::endl;
}