#include <iostream>
#include <vector>
#include <algorithm>
#include <iomanip>
using namespace std;

#define RREP(i,s,e) for (i = s; i >= e; i--)
#define rrep(i,n) RREP(i,n,0)
#define REP(i,s,e) for (i = s; i < e; i++)
#define rep(i,n) REP(i,0,n)
#define INF 100000000

typedef long long ll;

int main() {
    int i, j, k, x0, y0, n, sum;
    double ans;
    double dp[1<<13][13];
    double item[13][3];
    cin >> x0 >> y0 >> n;
    sum = 0;
    rep (i,n) {
        rep (j,3) cin >> item[i][j];
        sum += item[i][2];
    }
    rep (i,n) dp[1<<i][i] = (sum + 100) * (abs(item[i][0]-x0) + abs(item[i][1]-y0)) / 120 + item[i][2];
    REP (i,1,1<<n) {
        rep (j,n) {
            if (!(i & 1<<j)) {
                dp[i|1<<j][j] = INF;
                sum = 0;
                rep (k,n) if (!(i & 1<<k)) sum += item[k][2];
                rep (k,n) if (i & 1<<k) {
                    double cost = (sum+100) * (abs(item[k][0] - item[j][0]) + abs(item[k][1] - item[j][1])) / 120 + item[j][2];
                    dp[i|1<<j][j] = min(dp[i|1<<j][j],dp[i][k]+cost);
                }
            }
        }
    }
    ans = INF;
    rep (i,n) ans = min(ans,dp[(1<<n)-1][i]+100.0*(abs(item[i][0]-x0)+abs(item[i][1]-y0))/120);
    cout << fixed << setprecision(8) << ans << endl;
    return 0;
}