#include <iostream>
#include <iomanip>
using namespace std;

const int MAX_N = 20;
int x[MAX_N], y[MAX_N];
double w[MAX_N];
double dp[(1 << MAX_N)][MAX_N];

bool contains(int mask, int pos) {
    return (mask >> pos) & 1;
}

int calc_manhattan_dist(int x1, int y1, int x2, int y2) {
    return abs(x1 - x2) + abs(y1 - y2);
}

int main() {
    int n, x0, y0;
    cin >> x0 >> y0;
    cin >> n;

    for (int i = 0; i < n; i++) {
        cin >> x[i] >> y[i] >> w[i];
    }

    for (int mask = 1; mask < (1 << n); mask++) {
        for (int i = 0; i < n; i++) {
            if (!contains(mask, i)) continue;   // not valid

            int visited_cnt = 0;
            double prev_weight = w[i];
            for (int pos = 0; pos < n; pos++) {
                if (contains(mask, pos)) visited_cnt++;
                else prev_weight += w[pos];
            }


            // 酒屋から直接来た場合
            if (visited_cnt == 1) {
                int dist = calc_manhattan_dist(x0, y0, x[i], y[i]);
                dp[mask][i] = (prev_weight + 100.0) / 120.0 * dist + w[i];
                continue;
            }

            dp[mask][i] = 1e40;
            for (int prev = 0; prev < n; prev++) {
                if (!contains(mask, prev) || prev == i) continue;
                int dist = calc_manhattan_dist(x[i], y[i], x[prev], y[prev]);
                double cost = (prev_weight + 100.0) / 120.0 * dist + w[i];
                dp[mask][i] = min(dp[mask][i], dp[mask & ~(1 << i)][prev] + cost);
            }
        }
    }
    double ans = 1e40;
    for (int i = 0; i < n; i++) {
        int dist = calc_manhattan_dist(x0, y0, x[i], y[i]);
        ans = min(ans, dp[(1 << n) - 1][i] + 100.0 / 120.0 * dist);
    }
    cout << fixed << setprecision(10) << ans << endl;

    return 0;
}