#include <iostream>
#include <iomanip>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
#include <cmath>
using namespace std;
typedef long long i64;
typedef long double ld;
typedef pair<i64, i64> P;
#define rep(i, s, e) for (int i = (s); i <= (e); i++)

int sx, sy;

int n;
ld x[13], y[13], w[13];

ld dp[(1 << 13)];

ld dist(ld x1, ld y1, ld x2, ld y2)
{
    return abs(x1 - x2) + abs(y1 - y2);
}

int main()
{
    cin >> sx >> sy;
    cin >> n;
    rep(i, 0, n - 1) cin >> x[i] >> y[i] >> w[i];

    fill(dp, dp + (1 << 13), 1e9);

    ld w_sum = 0;
    rep(i, 0, n - 1) w_sum += w[i];

    rep(i, 1, (1 << n) - 1)
    {
        if (__builtin_popcount(i) == 1)
        {
            rep(j, 0, n - 1)
            {
                if (i & (1 << j))
                {
                    dp[i] = dist(x[j], y[j], sx, sy) * (w_sum + 100) / 120 + w[j];
                    break;
                }
            }
        }
        else
        {
            rep(j, 0, n - 1)
            {
                if (i & (1 << j))
                {
                    ld weight = 0;
                    int sub = i & ~(1 << j);
                    rep(k, 0, n - 1)
                    {
                        if (!(sub & (1 << k)))
                        {
                            weight += w[k];
                        }
                    }

                    rep(k, 0, n - 1)
                    {
                        if ((sub & (1 << k)))
                        {
                            ld d = dist(x[j], y[j], x[k], y[k]);
                            ld last = 0;

                            dp[i] = min(dp[i], dp[sub] + d * (weight + 100) / 120 + w[j] + last);
                        }
                    }
                    if (i == (1 << n) - 1)
                    {
                        dp[i] += dist(x[j], y[j], sx, sy) * 100 / 120;
                    }
                }

            }
        }
    }
    cout << fixed << setprecision(10);
    cout << dp[(1 << n) - 1] << endl;
}