#include <cassert>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <climits>
#include <cfloat>
#include <map>
#include <queue>
#include <set>
#include <cstring>
#include <vector>

using namespace std;
typedef long long ll;

int main() {
  ll X0, Y0;
  cin >> X0 >> Y0;
  int N;
  cin >> N;

  ll X[N];
  ll Y[N];
  double W[N];
  for (int i = 0; i < N; ++i) {
    cin >> X[i] >> Y[i] >> W[i];
  }

  int L = pow(2, N);
  vector<vector<double>> dp(L, vector<double>(N, -1.0));

  for (int c = 0; c < N; ++c) {
    for (int mask = 0; mask < L; ++mask) {
      if (__builtin_popcount(mask) != c) continue;

      double CW = 0;
      for (int i = 0; i < N; ++i) {
        if (mask >> i & 1) {
          // fprintf(stderr, "mask: %d, i: %d, cost: %f\n", mask, i, dp[mask][i]);
          continue;
        }

        CW += W[i];
      }

      double T = (CW + 100) * 1.0 / 120;

      if (c == 0) {
        for (int i = 0; i < N; ++i) {
          int nmask = mask | (1 << i);
          double cost = 0.0;
          ll dy = abs(Y[i] - Y0);
          ll dx = abs(X[i] - X0);
          cost += T * (dy + dx);
          cost += W[i];

          if (c == N - 1) {
            cost += (100.0 / 120.0) * (abs(Y[i] - Y0) + abs(X[i] - X0));
          }

          dp[nmask][i] = cost;
        }
      } else {
        for (int i = 0; i < N; ++i) {
          if (mask >> i & 1) continue;
          int nmask = mask | (1 << i);

          for (int j = 0; j < N; ++j) {
            if ((mask >> j & 1) == 0) continue;

            double cost = dp[mask][j];
            assert(cost >= 0.0);
            ll dy = abs(Y[j] - Y[i]);
            ll dx = abs(X[j] - X[i]);
            cost += T * (dy + dx);
            cost += W[i];

            if (c == N - 1) {
              cost += (100.0 / 120.0) * (abs(Y[i] - Y0) + abs(X[i] - X0));
            }

            if (dp[nmask][i] < 0) {
              dp[nmask][i] = cost;
            } else {
              dp[nmask][i] = min(dp[nmask][i], cost);
            }
          }
        }
      }
    }
  }

  double ans = LLONG_MAX;

  for (int i = 0; i < N; ++i) {
    ans = min(ans, dp[L - 1][i]);
  }

  cout << fixed << setprecision(10) << ans << endl;

  return 0;
}