#include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <cfloat>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
using namespace std;

#define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++)
#define repq(i,a,n) for(int (i)=(a); (i)<=(n); (i)++)
#define repr(i,a,n) for(int (i)=(a); (i)>=(n); (i)--)
#define all(v) begin(v), end(v)
#define pb(a) push_back(a)
#define fr first
#define sc second
#define INF 2000000000
#define int long long int

#define X real()
#define Y imag()
#define EPS (1e-10)
#define EQ(a,b) (abs((a) - (b)) < EPS)
#define EQV(a,b) ( EQ((a).X, (b).X) && EQ((a).Y, (b).Y) )
#define LE(n, m) ((n) < (m) + EPS)
#define LEQ(n, m) ((n) <= (m) + EPS)
#define GE(n, m) ((n) + EPS > (m))
#define GEQ(n, m) ((n) + EPS >= (m))

typedef vector<int> VI;
typedef vector<VI> MAT;
typedef pair<int, int> pii;
typedef long long ll;

typedef complex<double> P;
typedef pair<P, P> L;
typedef pair<P, double> C;

int dx[]={1, -1, 0, 0};
int dy[]={0, 0, 1, -1};
int const MOD = 1000000007;
ll mod_pow(ll x, ll n) {return (!n)?1:(mod_pow((x*x)%MOD,n/2)*((n&1)?x:1))%MOD;}
int madd(int a, int b) {return (a + b) % MOD;}
int msub(int a, int b) {return (a - b + MOD) % MOD;}
int mmul(int a, int b) {return (a * b) % MOD;}
int minv(int a) {return mod_pow(a, MOD-2);}
int mdiv(int a, int b) {return mmul(a, minv(b));}

namespace std {
    bool operator<(const P& a, const P& b) {
        return a.X != b.X ? a.X < b.X : a.Y < b.Y;
    }
}

int n;
double dp[1<<15][15];
double w[15];
double ptx[15], pty[15], sum = 0.0;

signed main() {
    cin >> ptx[0] >> pty[0];
    w[0] = 0.0;
    cin >> n;
    rep(i,0,n) {
        double x, y, z; cin >> x >> y >> z;
        ptx[i+1] = x, pty[i+1] = y;
        w[i+1] = z;
        sum += z;
    }
    n++;

    rep(i,0,1<<n) rep(j,0,n) dp[i][j] = 1e18;
    dp[0][0] = 0.0;
    rep(bit,0,1<<n) rep(p,0,n) {
        double nw = sum;
        rep(i,0,n) nw -= (bit >> i & 1 ? w[i] : 0);
        rep(i,0,n) {
            if(bit >> i & 1) continue;
            int nbit = bit | (1 << i);
            double dist = abs(ptx[i] - ptx[p]) + abs(pty[i] - pty[p]);
            double t = (nw + 100.0) / 120.0;
            dp[nbit][i] = min(dp[nbit][i], dp[bit][p] + t*dist + w[i]);
            // if(nbit == (1<<n)-1) printf("dp[%lld][%lld] = %.12lf\n", nbit, i, dp[nbit][i]);
        }
    }
    printf("%.12f\n", dp[(1<<n)-1][0]);
    return 0;
}