#include <bits/stdc++.h>
using namespace std;
int a, b, ax, ay, bx, by, n;
int x1[1010], Y1[1010], x2[1010], y2[1010], d[1010];
int dist2(int A, int B) {
  int dx = 0, dy = 0;
  if (x2[A] < x1[B])
    dx = x1[B] - x2[A];
  else if (x2[B] < x1[A])
    dx = x1[A] - x2[B];
  if (y2[A] < Y1[B])
    dy = Y1[B] - y2[A];
  else if (y2[B] < Y1[A])
    dy = Y1[A] - y2[B];
  return dx * dx + dy * dy;
}
double dist(int A, int B) {
  double dx = 0, dy = 0;
  if (x2[A] < x1[B])
    dx = x1[B] - x2[A];
  else if (x2[B] < x1[A])
    dx = x1[A] - x2[B];
  if (y2[A] < Y1[B])
    dy = Y1[B] - y2[A];
  else if (y2[B] < Y1[A])
    dy = Y1[A] - y2[B];
  return sqrt(dx * dx + dy * dy);
}
int main() {
  cin >> a >> b >> ax >> ay >> bx >> by >> n;
  for (int i = 0; i < n; i++) {
    cin >> x1[i] >> Y1[i] >> x2[i] >> y2[i];
    if (x1[i] == x2[i]) {
      if (Y1[i] > y2[i]) swap(Y1[i], y2[i]);
    } else {
      if (x1[i] > x2[i]) swap(x1[i], x2[i]);
    }
  }
  x1[n] = x2[n] = ax;
  Y1[n] = y2[n] = ay;
  x1[n + 1] = x2[n + 1] = bx;
  Y1[n + 1] = y2[n + 1] = by;
  queue<int> Q;
  Q.push(n);
  fill(d, d + n + 2, 1000000007LL);
  d[n] = 0;
  while (Q.size()) {
    int cur = Q.front();
    Q.pop();
    if (cur == n + 1) break;
    for (int i = 0; i < n + 2; i++) {
      if (d[i] > d[cur] + 1 && dist2(cur, i) <= a * a) {
        d[i] = d[cur] + 1;
        Q.push(i);
      }
    }
  }
  if (d[n + 1] == 1000000007LL) {
    cout << -1;
    return 0;
  }
  double ans = 1000000007LL;
  for (int i = 0; i < n + 1; i++)
    if (d[i] == d[n + 1] - 1) {
      ans = min(ans, (a + b) * d[i] + dist(i, n + 1));
    }
  cout << ans;
}
