#include<iostream>
#include<string>
#include<map>
#include<vector>
#include<list>
#include<queue>
#include<stack>
#include<deque>
#include<set>
#include<bitset>
#include<functional>
#include<utility>
#include<iterator>
#include<algorithm>
#include<sstream>
#include<fstream>
#include<cstdio>
#include<cstdlib>
#include<cmath>
#include<ctime>
#include<cstring>
#include<iomanip>
using namespace std;
#define len(val) static_cast<int>(val.size())
#define rep(i, N) for(int i=0; i<N; i++)
typedef long long ll;
typedef pair<int, int> P;

const int MAXN = 14;
int sx, sy;
int n;
int xs[MAXN], ys[MAXN];
double wss[MAXN];
double wsum = 0;
double dp[1 << MAXN][MAXN];
double d[MAXN][MAXN];
const int INF = 1e9;

double dfs(int s, int v)
{
    if(dp[s][v] >= 0) return dp[s][v];

    if(s == (1<<n)-1 && v == 0){
        return dp[s][v] = 0;
    }
    double res = INF;
    for(int u=0; u<n; u++){
        if(!(s>>u & 1)){
            double wes = wsum;
            for(int i=0; i<n; i++){
                if(s>>i & 1) wes -= wss[i];
            }
            res = min(res, dfs(s|1<<u, u)+(double)d[v][u]*(double)(wes+100)/120 + wss[u]);
        }
    }
    return dp[s][v] = res;
}

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    cin >> sx >> sy;
    cin >> n;
    rep(i, n+1){
        if(i == 0){
            xs[i] = sx; ys[i] = sy; wss[i] = 0;
            continue;
        }
        cin >> xs[i] >> ys[i] >> wss[i];
        wsum += wss[i];
    }
    n++;
    rep(i, n){
        rep(j, n){
            if(i == j){
                d[i][j] = INF;
            }else{
                d[i][j] = abs(xs[i]-xs[j])+abs(ys[i]-ys[j]);
            }
        }
    }
    memset(dp, -1, sizeof(dp));
    cout << setprecision(8) << dfs(0, 0) << endl;
}