//#include <tourist>
#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
typedef long long ll;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef pair<ll, ll> p;
const int INF = 1e9;
const ll LINF = ll(1e18);
const int MOD = 1000000007;
const int dx[4] = {0, 1, 0, -1}, dy[4] = {-1, 0, 1, 0};
const int Dx[8] = {0, 1, 1, 1, 0, -1, -1, -1}, Dy[8] = {-1, -1, 0, 1, 1, 1, 0, -1};
#define yes cout << "Yes" << endl
#define YES cout << "YES" << endl
#define no cout << "No" << endl
#define NO cout << "NO" << endl
#define rep(i, n) for (int i = 0; i < n; i++)
#define ALL(v) v.begin(), v.end()
#define debug(v)          \
    cout << #v << ":";    \
    for (auto x : v)      \
    {                     \
        cout << x << ' '; \
    }                     \
    cout << endl;
template <class T>
bool chmax(T &a, const T &b)
{
    if (a < b)
    {
        a = b;
        return 1;
    }
    return 0;
}
template <class T>
bool chmin(T &a, const T &b)
{
    if (b < a)
    {
        a = b;
        return 1;
    }
    return 0;
}
//cout<<fixed<<setprecision(15);有効数字15桁
//-std=c++14
//g++ yarudake.cpp -std=c++17 -I .
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;
    double xs, ys;
    cin >> xs >> ys >> n;
    vector<double> x(n + 1), y(n + 1), w(n + 1);
    x[0] = xs;
    y[0] = ys;
    w[0] = 0;
    double sum = 0;

    rep(i, n)
    {
        cin >> x[i + 1] >> y[i + 1] >> w[i + 1];
        sum += w[i + 1];
    }
    n++;
    vector<vector<double>> dp(1 << n, vector<double>(n, 100000000));
    dp[1][0] = 0;
    for (int i = 1; i < (1 << n); i++)
    {
        double sumt = sum;
        rep(j, n)
        {
            if (i & (1 << j))
                sumt -= w[j];
        }
        rep(j, n)
        {
            if (!(i & (1 << j)))
                continue;
            rep(k, n)
            {
                if (!(i & (1 << k)))
                {
                    double dist = abs(x[j] - x[k]) +abs(y[j] - y[k]);
                    chmin(dp[i | (1 << k)][k], dp[i][j] + (sumt + 100)* dist/120);
                }
            }
        }
    }
    double ans =100000000;
    rep(i,n){
        double dist = abs(x[0] - x[i]) + abs(y[0] - y[i]);
        chmin(ans,dp[(1<<n)-1][i]+100*dist/120);
    }
    cout << fixed << setprecision(15);
    cout<<ans+sum<<"\n";
}