#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int INF = 1e9;
const ll LINF = 1e18;
template<class S,class T> ostream& operator << (ostream& out,const pair<S,T>& o){ out << "(" << o.first << "," << o.second << ")"; return out; }
template<class T> ostream& operator << (ostream& out,const vector<T> V){ for(int i = 0; i < V.size(); i++){ out << V[i]; if(i!=V.size()-1) out << " ";} return out; }
template<class T> ostream& operator << (ostream& out,const vector<vector<T> > Mat){ for(int i = 0; i < Mat.size(); i++) { if(i != 0) out << endl; out << Mat[i];} return out; }
template<class S,class T> ostream& operator << (ostream& out,const map<S,T> mp){ out << "{ "; for(auto it = mp.begin(); it != mp.end(); it++){ out << it->first << ":" << it->second; if(mp.size()-1 != distance(mp.begin(),it)) out << ", "; } out << " }"; return out; }

/*
 <url:https://yukicoder.me/problems/no/134>
 問題文============================================================
 =================================================================
 解説=============================================================
 ================================================================
 */

typedef long double ld;
ld solve(){
    ld res = INF;
    
    ll x,y; cin >> x >> y;
    int N; cin >> N;
    vector<pll> ps(N+1);
    vector<ld> w(N+1);
    
    ps[0] = {x,y};
    ld W = 0;
    for(int i = 1; i <= N;i++){
        cin >> ps[i].first >> ps[i].second >> w[i];
        W += w[i];
    }

    N++;
    vector<vector<ld>> dp(1<<N,vector<ld>(N,INF));
    dp[0][0] = 0;
    for(int i = 0; i < (1<<N);i++){
        for(int j = 0; j < N;j++){
            if(dp[i][j]>=INF-10) continue;
            ld haveW = W;
            for(int k = 0; k < N;k++) if(!((i>>k)&1)) haveW -= w[k];
            for(int k = 0; k < N;k++){
                if((i>>k)&1) continue;
                dp[i|(1<<k)][k] = min(dp[i|(1<<k)][k],dp[i][j]+(abs(ps[j].first-ps[k].first)+abs(ps[j].second-ps[k].second))*(haveW+100)/120.+w[k]);
            }
        }
    }
    res = dp[(1<<N)-1][0];
    return res;
}
int main(void) {
    cin.tie(0); ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(12) << solve() << endl;
    return 0;
}