#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    vector<int> X(1), Y(1);
    int N;
    cin >> X[0] >> Y[0] >> N;
    X.resize(N + 1); Y.resize(N + 1);
    vector<double> W(N + 1);
    for(int i = 1; i <= N; ++i) cin >> X[i] >> Y[i] >> W[i];
    double S = accumulate(begin(W), end(W), 0.0);
    
    constexpr double inf = 1e+30;
    vector<vector<double>> dp(1 << (N + 1), vector<double>(N + 1, inf));
    dp[0][0] = 0;
    for(int mask = 0; mask < 1 << (N + 1); ++mask){
        for(int i = 0; i <= N; ++i){
            if(dp[mask][i] == inf)  continue;
            double T = S;
            for(int j = 0; j <= N; ++j){
                if(mask >> j & 1)   T -= W[j];
            }
            T = (T + 100.0) / 120.0;
            for(int j = 0; j <= N; ++j){
                if(mask >> j & 1)   continue;
                int dist = abs(X[i] - X[j]) + abs(Y[i] - Y[j]);
                chmin(dp[mask | (1 << j)][j], dp[mask][i] + T * dist + W[j]);
            }
        }
    }

    cout << fixed << setprecision(10);
    cout << dp[(1 << (N + 1)) - 1][0] << endl;

    return 0;
}