#include <bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    double x0,y0; cin >> x0 >> y0;
    int N; cin >> N;
    vector<pair<double,double>> XY(N+1);
    XY.at(0) = {x0,y0};
    vector<double> W(N+1);
    double sumw = 0;
    for(int i=1; i<=N; i++){
        int x,y; double w; cin >> x >> y >> w;
        XY.at(i) = {x,y},W.at(i) = w,sumw += w;
    }

    int n2 = 2<<N;
    vector<vector<double>> dp(n2,vector<double>(N+1,1e18));
    dp.at(1).at(0) = 0;
    for(int i=1; i<n2; i++){
        double noww = sumw;
        for(int k=0; k<=N; k++) if((i&(1<<k))) noww -= W.at(k);
        double time = (noww+100)/120;
        for(int k=0; k<=N; k++) if(i&(1<<k)){
            auto [x1,y1] = XY.at(k);
            for(int l=0; l<=N; l++) if(!(i&(1<<l))){
                auto [x2,y2] = XY.at(l);
                double cost = (abs(x2-x1)+abs(y2-y1))*time;
                dp.at(i+(1<<l)).at(l) = min(dp.at(i+(1<<l)).at(l),dp.at(i).at(k)+cost);
            }
        }        
    } 

    double answer = 1e18;
    for(int i=0; i<=N; i++){
        auto [x,y] = XY.at(i);
        double time = 100.0/120;
        double cost = time*(abs(x-x0)+abs(y-y0));
        answer = min(answer,dp.at(n2-1).at(i)+cost);
    }
    answer += sumw;
    cout << fixed << setprecision(20) << answer << endl;
}