#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1000 + 10;
struct haogou {
  int x1, x2, y1, y2;
} hg[MAXN];
double dis[MAXN][MAXN], d[MAXN];
int f[MAXN];
bool vis[MAXN];
int n, t1, t2;
double hgdis(int i, int j) {
  int x1, x2, y1, y2;
  x1 = max(hg[i].x1, hg[j].x1);
  x2 = min(hg[i].x2, hg[j].x2);
  y1 = max(hg[i].y1, hg[j].y1);
  y2 = min(hg[i].y2, hg[j].y2);
  x2 = max(x1 - x2, 0);
  y2 = max(y1 - y2, 0);
  return sqrt(x2 * x2 + y2 * y2);
}
void bfs() {
  int i, k;
  queue<int> q;
  for (i = 0; i <= n; i++) d[i] = -1;
  vis[0] = 1, d[0] = 0, f[0] = 0;
  q.push(0);
  while (!q.empty()) {
    k = q.front();
    q.pop();
    for (i = 0; i < n; i++) {
      if (dis[k][i] <= t1) {
        if (dis[k][i] + f[k] * t2 < d[i] || d[i] < 0) {
          d[i] = dis[k][i] + f[k] * t2;
          f[i] = f[k] + 1;
          if (!vis[i]) {
            vis[i] = 1;
            q.push(i);
          }
        }
      }
    }
    vis[k] = 0;
  }
}
int main() {
  int i, j;
  scanf("%d%d", &t1, &t2);
  t2 += t1;
  scanf("%d%d%d%d%d", &hg[0].x1, &hg[0].y1, &hg[1].x1, &hg[1].y1, &n);
  hg[0].x2 = hg[0].x1, hg[0].y2 = hg[0].y1;
  hg[1].x2 = hg[1].x1, hg[1].y2 = hg[1].y1;
  n += 2;
  for (i = 2; i < n; i++) {
    scanf("%d%d%d%d", &hg[i].x1, &hg[i].y1, &hg[i].x2, &hg[i].y2);
    if (hg[i].x1 > hg[i].x2) swap(hg[i].x1, hg[i].x2);
    if (hg[i].y1 > hg[i].y2) swap(hg[i].y1, hg[i].y2);
  }
  for (i = 1; i < n; i++)
    for (j = 0; j < i; j++) dis[i][j] = dis[j][i] = hgdis(i, j);
  bfs();
  if (d[1] < 0)
    cout << "-1\n";
  else
    printf("%.10f\n", d[1]);
  return 0;
}
