#include "bits/stdc++.h"
#define REP(i,n,N) for(int i=(n); i<(N); i++)
#define RREP(i,n,N) for(ll i=(N-1); i>=n; i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define p(s) cout<<(s)<<endl
#define p2(a,b) cout<<(a)<<" "<<(b)<<endl
#define v2(T) vector<vector<T>>
typedef long long ll;
using namespace std;
const ll mod=1e9+7;
const int inf=1e9;

pair<int,int> yx[13];
double W[13];
double dp[1<<13][13];

double cost(int a, int b, double w){
    return (abs(yx[a].first-yx[b].first) + abs(yx[a].second-yx[b].second)) * (w+100.0)/120.0 + W[a];
}
int main() {
    int sx,sy,n;
    cin>>sx>>sy>>n;
    double sum=0;
    REP(i,0,n){
        int x,y;
        cin>>x>>y>>W[i];
        yx[i] = {y,x};
        sum += W[i];
    }
    REP(mask,0,1<<n) REP(i,0,n) dp[mask][i] = inf;
    dp[0][0] = 0;
    REP(i,0,n) dp[1<<i][i] = (abs(yx[i].first-sy) + abs(yx[i].second-sx)) * (sum + 100.0)/120.0 + W[i];
    REP(mask,1,1<<n){
        double sumW=sum;
        vector<int> ca;
        REP(i,0,n){
            if((mask & (1<<i))){
                sumW -= W[i];
                ca.push_back(i);
            }
        }
        REP(i,0,n){
            if((mask & (1<<i))) continue;
            for(auto j:ca){
                dp[mask | (1<<i)][i] = min(dp[mask|(1<<i)][i], dp[mask][j] + cost(i,j,sumW));
                //cout<<i<<" "<<j<<" "<<cost(i,j,sumW)<<endl;
            }
        }
    }
    double ans=1e9;
    REP(i,0,n){
        ans = min(ans, dp[(1<<n)-1][i] + (abs(yx[i].first-sy) + abs(yx[i].second-sx))* 5.0/6);
    }
    printf("%.8lf\n", ans);
    return 0;
}