#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <iomanip>

#define REP(i, a, b) for (int i = int(a); i < int(b); i++)
#ifdef _DEBUG_
#define dump(val) cerr << __LINE__ << ":\t" << #val << " = " << (val) << endl
#else
#define dump(val)
#endif

using namespace std;

typedef long long int ll;

template<typename T>
vector<T> make_v(size_t a, T b) {
    return vector<T>(a, b);
}

template<typename... Ts>
auto make_v(size_t a, Ts... ts) {
    return vector<decltype(make_v(ts...))>(a, make_v(ts...));
}

template<typename T>
void chmin(T &a, T b) {
    a = min(a, b);
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int x, y, n;
    cin >> x >> y >> n;
    vector<int> X(n), Y(n);
    vector<double> W(n);
    double Wsum = 0;
    REP(i, 0, n) {
        cin >> X[i] >> Y[i] >> W[i];
        Wsum += W[i];
    }

    auto dp = make_v(1 << n, n, double(1e+15));
    REP(i, 0, n) {
        dp[1 << i][i] = (abs(x - X[i]) + abs(y - Y[i])) * (Wsum + 100) / 120;
    }
    REP(i, 1, 1 << n) {
        double w = 0.0;
        REP(j, 0, n) {
            if (((i >> j) & 1) == 0) {
                w += W[j];
            }
        }
        REP(j, 0, n) {
            REP(k, 0, n) {
                int nxt = i | (1 << k);
                if (i == nxt) continue;
                int dis = abs(X[j] - X[k]) + abs(Y[j] - Y[k]);
                double cost = dis * (w + 100) / 120;
                chmin(dp[nxt][k], dp[i][j] + cost);
            }
        }
    }

    double ans = 1e+15;
    REP(i, 0, n) {
        chmin(ans, dp[(1 << n) - 1][i] + (abs(x - X[i]) + abs(y - Y[i])) * 100.0 / 120);
    }
    cout << fixed << setprecision(15) << ans + Wsum << endl;

    return 0;
}