#include <bits/stdc++.h>
using namespace std;
template <typename T>
using min_pq = priority_queue<T, vector<T>, greater<T>>;
template <typename T>
using max_pq = priority_queue<T>;
const int inf = 2e9 + 5;
const long long l_inf = 2e18 + 5;
const int mod_v = 1e9 + 7;
const int max_n = 1e5 + 5;
const int dx[4] = {-1, 0, 1, 0};
const int dy[4] = {0, 1, 0, -1};
template <typename T>
T gcd(T a, T b) {
  while (b) {
    T temp = a % b;
    a = b;
    b = temp;
  }
  return a;
}
template <typename T>
tuple<T, T, T> egcd(T a, T b) {
  T x1 = 1, x2 = 0, y1 = 0, y2 = 1;
  while (b) {
    T q = a / b, r = a % b;
    T new_x = x1 - q * x2, new_y = y1 - q * y2;
    x1 = x2, y1 = y2, x2 = new_x, y2 = new_y;
    a = b, b = r;
  }
  return make_tuple(a, x1, y1);
}
inline long long lcm(long long a, long long b) { return a * b / gcd(a, b); }
template <typename T>
inline T mod(T a, T b = mod_v) {
  return (a % b + b) % b;
}
template <typename T>
inline T mod_inv(T a, T b = mod_v) {
  return mod(get<1>(egcd(a, b)), b);
}
template <typename T>
inline T sum(T a, T b, T m = mod_v) {
  return mod(mod(a, m) + mod(b, m), m);
}
template <typename T>
inline T difference(T a, T b, T m = mod_v) {
  return mod(mod(a, m) - mod(b, m), m);
}
inline long long product(long long a, long long b, long long m = mod_v) {
  return mod(mod(a, m) * mod(b, m), m);
}
inline long long quotient(long long a, long long b, long long m = mod_v) {
  return mod(mod(a, m) * mod_inv(b, m), m);
}
template <typename T, typename T2>
ostream &operator<<(ostream &s, const pair<T, T2> &p) {
  return s << p.first << ' ' << p.second << ' ';
}
template <typename T, typename T2>
istream &operator>>(istream &s, pair<T, T2> &p) {
  return s >> p.first >> p.second;
}
template <typename T>
ostream &operator<<(ostream &s, const vector<T> &v) {
  for (auto it : v) s << it << ' ';
  return s;
}
template <typename T>
istream &operator>>(istream &s, vector<T> &v) {
  for (auto it = (v).begin(), it_ = (v).end(); it != it_; ++it) s >> *it;
  return s;
}
template <typename T>
void read_range(T beg, T end) {
  while (beg != end) cin >> *beg++;
}
template <typename T>
void print_range(T beg, T end) {
  while (beg != end) cout << *beg++ << ' ';
}
struct reader {
  template <typename T>
  reader &operator,(T &v) {
    cin >> v;
    return *this;
  }
} rdr;
struct debugger {
  template <typename T>
  debugger &operator,(const T &v) {
    cerr << v << ", ";
    return *this;
  }
} dbg;
int n, m, d[3005][3005], l1, l2, s1, t1, s2, t2, res;
vector<int> adj[3005];
void bfs(int s) {
  for (int i = 1; i <= n; ++i) d[s][i] = inf;
  d[s][s] = 0;
  queue<int> q;
  q.push(s);
  while (!q.empty()) {
    int u = q.front();
    q.pop();
    for (int v : adj[u])
      if (d[s][v] > d[s][u] + 1) {
        d[s][v] = d[s][u] + 1;
        q.push(v);
      }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin >> n >> m;
  for (int i = 0, i_ = (m); i < i_; ++i) {
    int u, v;
    rdr, u, v;
    ;
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
  cin >> s1 >> t1 >> l1;
  cin >> s2 >> t2 >> l2;
  for (int i = 1; i <= n; ++i) bfs(i);
  if (d[s1][t1] > l1 or d[s2][t2] > l2) {
    cout << -1;
    return 0;
  }
  res = d[s1][t1] + d[s2][t2];
  for (int k = 0; k < 2; ++k) {
    for (int i = 1; i <= n; ++i)
      for (int j = 1; j <= n; ++j) {
        if (d[s1][i] + d[i][j] + d[j][t1] > l1 or
            d[s2][i] + d[i][j] + d[j][t2] > l2)
          continue;
        res = min(res, d[s1][i] + d[s2][i] + d[i][j] + d[j][t1] + d[j][t2]);
      }
    swap(s1, t1);
  }
  cout << m - res;
  return 0;
}
