#include <iostream>
#include <algorithm>
#include <iomanip>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 1000000007;
using ll = long long;
using u32 = uint32_t;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max() / 32 * 15 + 208;

template <class T, class U>
vector<T> make_v(U size, const T& init){ return vector<T>(static_cast<size_t>(size), init); }

template<class... Ts, class U>
auto make_v(U size, Ts... rest) { return vector<decltype(make_v(rest...))>(static_cast<size_t>(size), make_v(rest...)); }

template<class T> void chmin(T &a, const T &b){ a = (a < b ? a : b); }
template<class T> void chmax(T &a, const T &b){ a = (a > b ? a : b); }

int main() {
    int x, y, n;
    cin >> x >> y >> n;
    vector<int> xs(n), ys(n);
    vector<double> ws(n);
    for (int i = 0; i < n; ++i) {
        cin >> xs[i] >> ys[i] >> ws[i];
    }
    auto dp = make_v(n, 1 << n, INF<double>);
    vector<double> ww(1<<n);
    for (int i = 1; i < (1 << n); ++i) {
        for (int j = 0; j < n; ++j) {
            if(i & (1 << j)){
                ww[i] = ww[i^(1 << j)]+ws[j];
                break;
            }
        }
    }
    for (int i = 0; i < n; ++i) {
        dp[i][(1 << n)-1-(1 << i)] = (abs(x-xs[i])+abs(y-ys[i]))*(100+ww.back())/120.0+ws[i];
    }


    for (int i = (1 << n)-2; i >= 0; --i) {
        for (int k = 0; k < n; ++k) {
            if(not (i & (1 << k))) {
                for (int j = 0; j < n; ++j) {
                    if(k != j && not (i & (1 << j))){
                        int from = i ^ (1 << j);
                        dp[j][i] = min(dp[j][i], dp[k][from] + ws[j]+ (100+ww[from])/120.0*(abs(xs[k]-xs[j])+abs(ys[k]-ys[j])));
                    }
                }
            }
        }
    }
    double ans = INF<double>;
    for (int i = 0; i < n; ++i) {
        ans = min(ans, dp[i].front()+(abs(xs[i]-x)+abs(ys[i]-y))/1.2);
    }
    printf("%.10lf\n", ans);
    return 0;
}