#include <bits/stdc++.h>
using namespace std;
const double INF = 1ll << 60;

int N, X0, Y0, X[20], Y[20];
double W[20];

bool done[1<<20][20];
double dp[1<<20][20];

double solve(int used, int last, double wsum){
    if(done[used][last])
        return dp[used][last];
    
    double res = INF;
    double t = (wsum + 100) / 120;
    
    if(used == ((1 << N) - 1)){
        double d = abs(X[last] - X0) + abs(Y[last] - Y0);
        res = min(res, d * t);
    } else {
        for(int i=0;i<N;i++){
            if((used >> i) & 1)
                continue;
        
            double d = abs(X[last] - X[i]) + abs(Y[last] - Y[i]);
            res = min(res, d * t + W[i] + solve(used | (1 << i), i, wsum - W[i]));
        }
    }
    
    done[used][last] = true;
    return dp[used][last] = res;
}


int main(){
    cin >> X0 >> Y0;
    cin >> N;
    
    for(int i=0;i<N;i++)
        cin >> X[i] >> Y[i] >> W[i];
    
    double wsum = 0;
    for(int i=0;i<N;i++)
        wsum += W[i];
    
    double res = INF;
    for(int i=0;i<N;i++){
        double t = (wsum + 100) / 120;
        double d = abs(X[i] - X0) + abs(Y[i] - Y0);
        
        res = min(res, d * t + W[i] + solve(1 << i, i, wsum - W[i]));
    }
    
    printf("%.10f\n", res);
    return 0;
}