/* -*- coding: utf-8 -*-
 *
 * 134.cc: No.134 走れ!サブロー君 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 13;
const int NBITS = 1 << MAX_N;

const double DINF = 1e60;

/* typedef */

/* global variables */

int xs[MAX_N], ys[MAX_N];
double wis[MAX_N], wsums[NBITS], dp[NBITS][MAX_N];

/* subroutines */

inline int mdist(int x0, int y0, int x1, int y1) {
  return abs(x1 - x0) + abs(y1 - y0);
}

inline double btime(int bits) { return (wsums[bits] + 100) / 120; }

/* main */

int main() {
  int sx, sy;
  cin >> sx >> sy;

  int n;
  cin >> n;

  int nbits = 1 << n;
  double wsum = 0.0;
  for (int i = 0; i < n; i++) {
    cin >> xs[i] >> ys[i] >> wis[i];
    wsum += wis[i];
  }

  for (int bits = 0; bits < nbits; bits++) {
    wsums[bits] = wsum;
    for (int i = 0, bi = 1; i < n; i++, bi <<= 1) {
      if (bits & bi) wsums[bits] -= wis[i];
      dp[bits][i] = DINF;
    }
  }

  for (int i = 0, bi = 1; i < n; i++, bi <<= 1)
    dp[bi][i] = mdist(sx, sy, xs[i], ys[i]) * btime(0) + wis[i];

  for (int bits = 0; bits < nbits; bits++)
    for (int i = 0; i < n; i++)
      if (dp[bits][i] < DINF)
	for (int j = 0, bj = 1; j < n; j++, bj <<= 1)
	  if (! (bits & bj)) {
	    int bitsj = bits | bj;
	    double d =
	      dp[bits][i] + mdist(xs[i], ys[i], xs[j], ys[j]) * btime(bits)
	      + wis[j];
	    if (dp[bitsj][j] > d) dp[bitsj][j] = d;
	  }

  double mint = DINF;
  for (int i = 0; i < n; i++)
    if (dp[nbits - 1][i] < DINF) {
      double t =
	dp[nbits - 1][i] + mdist(xs[i], ys[i], sx, sy) * 100.0 / 120;
      if (mint > t) mint = t;
    }

  printf("%.9lf\n", mint);
  return 0;
}