#include <bits/stdc++.h>
using namespace std;
#define all(c) (c).begin(),(c).end()
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;i--)
#define REP(i,m,n) for(int i=(int)(m);i<(int)(n);i++)
#define rep(i,n) REP(i,0,n)
#define iter(c) __typeof((c).begin())
#define tr(it,c) for(iter(c) it=(c).begin();it!=(c).end();it++)
#define pb(a) push_back(a)
#define pr(a) cout<<(a)<<endl
#define PR(a,b) cout<<(a)<<" "<<(b)<<endl
#define R cin>>
#define F first
#define S second
#define ll long long
bool check(int n,int m,int x,int y){return (x<0||x>=n||y<0||y>=m)?false:true;}
const ll MAX=1000000007,MAXL=1LL<<60,dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};
typedef pair<int,int> P;
typedef pair<P,double> P2;

double D(int x1, int y1, int x2, int y2) {
  return abs(x1-x2)+abs(y1-y2);
}

double T(double w) {
  return (w+100.0)/120.0;
}

int main() {
  int xx,yy,n;
  cin >> xx >> yy >> n;
  P2 a[n+1];
  double sum=0;
  for(int i=0; i<n; i++) {
    cin >> a[i].F.F >> a[i].F.S >> a[i].S;
    sum+=a[i].S;
  }
  a[n].F.F=xx;a[n].F.S=yy;a[n].S=0;
  double dp[(1<<(n+1))][n+1];
  fill(dp[0],dp[(1<<(n+1))],MAXL);
  for(int i=0; i<n; i++) {
    double d=D(xx,yy,a[i].F.F,a[i].F.S);
    dp[(1<<i)][i]=d*T(sum)+a[i].S;
  }
  for(int t=1; t<(1<<(n+1)); t++) {
    for(int j=0; j<=n; j++) {
      if(!(t&(1<<j))) continue;
      if(dp[t][j]==MAXL) continue;
      for(int i=0; i<=n; i++) {
	if(t&(1<<i)) continue;
	double ww=sum;
	for(int k=0; k<n; k++) {
	  if(t&(1<<k)) ww-=a[k].S;
	}
	double d=D(a[j].F.F,a[j].F.S,a[i].F.F,a[i].F.S);
	dp[t|(1<<i)][i]=min(dp[t|(1<<i)][i],dp[t][j]+d*T(ww)+a[i].S);
      }
    }
  }
  printf("%.10f\n",dp[(1<<(n+1))-1][n]);
  return 0;
}