#include <bits/stdc++.h> 

using namespace std;

double X[15];
double Y[15];
double W[15];
double dp[1 << 14][14];
int N;

int main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    cin >> X[0] >> Y[0];
    W[0] = 0;
    cin >> N;
    for (int i = 1; i <= N; i++)
    {
        cin >> X[i] >> Y[i] >> W[i];
    }

    for (int i = 0; i < (1 << (N+1)); i++)
    {
        for (int j = 0; j <= N; j++)
        {
            dp[i][j] = 1e18;
        }
    }
    dp[1][0] = 0;

    for (int i = 0; i < (1 << (N + 1)); i++)
    {
        double weight = 0;
        for (int j = 0; j <= N; j++)
        {
            if ((i & (1 << j)) == 0)
            {
                weight += W[j];
            }
        }
        //cout << i << ' ' << weight << '\n';
        for (int j = 0; j <= N; j++)
        {
            if (dp[i][j] >= 1e18) continue;
            for (int k = 0; k <= N; k++)
            {
                if ((i & (1 << k)) != 0)
                {
                    continue;
                }
                double s = (100 + weight) / 120;
                double d = abs(X[j] - X[k]) + abs(Y[j] - Y[k]);
                double time = d * s;
                time += W[k];
                //cout << i << ' ' << j << ' ' << k << ' ' << time << '\n';
                dp[i + (1 << k)][k] = min(dp[i + (1 << k)][k], dp[i][j] + time);
            }
        }
    }

    double res = 1e18;

    for (int j = 0; j <= N; j++)
    {
        if (dp[(1 << (N + 1)) - 1][j] >= 1e18)
        {
            continue;
        }
        double dx = abs(X[j] - X[0]);
        double dy = abs(Y[j] - Y[0]);
        double D = dx + dy;
        D *= 5;
        D /= 6;
        res = min(res, D + dp[(1 << (N + 1)) - 1][j]);
    }

    cout << fixed;
    cout.precision(9);

    cout << res << '\n';

    return 0;
}