#include <sstream>
#include <string>
#include <vector>
#include <map>
#include <algorithm>
#include <iostream>
#include <utility>
#include <set>
#include <cctype>
#include <queue>
#include <stack>
#include <cstdio>
#include <cstdlib>
#include <cmath>

#define INF 1000000000

using namespace std;
typedef long long ll;

const int MAXN = 20;
int X0, Y0;
int N;
int x[MAXN], y[MAXN];
double w[MAXN];
double dp[MAXN][1<<MAXN];

double dfs(int v, int S) {
    if (dp[v][S] >= 0) return dp[v][S];
    if (S == (1<<N)-1 && v == 0) return dp[v][S] = 0;
    double ret = INF;
    double W = 0;
    for (int i = 0; i < N; i++) {
        if (!(S>>i & 1)) W += w[i];
    }
    for (int u = 0; u < N; u++) {
        if (!(S>>u&1)) {
            double dist = abs(x[v]-x[u]) + abs(y[v]-y[u]);
            ret = min(ret, dfs(u, S|(1<<u)) + dist * (W+100) / 120.);
        }
    }
    return dp[v][S] = ret;
}

int main(void) {
    cin >> x[0] >> y[0];
    w[0] = 0;
    cin >> N;
    double W = 0;
    for (int i = 1; i <= N; i++) {
        cin >> x[i] >> y[i] >> w[i];
        W += w[i];
    }
    N++;
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < (1<<N); j++) dp[i][j] = -1;
    }
    printf("%lf\n", dfs(0, 0) + W);
    return 0;
}