#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

double dp[1<<14][14];
const double INF = numeric_limits<double>::max();

int main(){
    int N;
    vi X(1), Y(1);
    cin >> X[0] >> Y[0] >> N;
    N++;
    vector<double> W(N), wsum(1ull<<N);
    X.resize(N);
    Y.resize(N);
    FOR(i, 1,N){
        cin >> X[i] >> Y[i] >> W[i];
    }
    rep(i, 1 << N){
        rep(j, N)if(i >> j&1)wsum[i] += W[j];
    }
    rep(i, 1<<N)rep(j, N)dp[i][j] = INF;
    dp[1][0] = 0;

    for(int S = 1; S < (1 << N); ++S){
        rep(i, N)if(dp[S][i]<INF-100){
            rep(j, N){
                int d = abs(X[i] - X[j]) + abs(Y[i] - Y[j]);
                double t = (wsum[S] + 100)*d / 120.0;
                if(S>>j&1)smin(dp[1 << j | S][j], dp[S][i]+t);
                else smin(dp[1 << j | S][j], dp[S][i]+t + W[j]);
            }
        }
    }
    cout << setprecision(20) << dp[(1 << N) - 1][0] << endl;
}