#include<bits/stdc++.h>
using namespace std;
const int nmax=15;
double x[nmax],y[nmax],w[nmax];
double dis(int i,int j){
  return abs(x[i]-x[j])+abs(y[i]-y[j]);
}
int main(){
  double p,q;cin >> p >> q;
  int n;cin >> n;
  double aw=0;
  for(int i=0;i<n;i++){
    cin >> x[i] >> y[i] >> w[i];
    aw+=w[i];
  }
  x[n]=p,y[n]=q;
  vector<vector<double>> dp(1<<n,vector<double>(n,1e9));
  for(int i=0;i<n;i++){
    dp[1<<i][i]=dis(i,n)*(aw+100)/120;
  }
  for(int i=1;i<(1<<n);i++){
    double wt=0;
    for(int j=0;j<n;j++){
      if(!((i>>j)&1)){
        wt+=w[j];
      }
    }
    for(int j=0;j<n;j++){
      if((i>>j)&1){
        continue;
      }
      for(int k=0;k<n;k++){
        if((i>>k)&1){
          dp[i|(1<<j)][j]=min(dp[i|(1<<j)][j],dp[i][k]+dis(j,k)*(wt+100)/120);
        }
      }
    }
  }
  double ans=1e9;
  for(int i=0;i<n;i++){
    ans=min(ans,dp[(1<<n)-1][i]+dis(i,n)*100/120);
  }
  cout << fixed << setprecision(10) << ans+aw << endl;
}