#include <bits/stdc++.h>
using namespace std;
int n, m, a, b, fr, k1, k2;
int dist[3005][3005];
bool flag[3005][3005];
vector<int> v[3005];
queue<int> q;
int main() {
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= m; i++) {
    scanf("%d %d", &a, &b);
    v[a].push_back(b);
    v[b].push_back(a);
  }
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= n; j++) dist[i][j] = 1e9;
  memset(flag, 1, sizeof(flag));
  for (int k = 1; k <= n; k++) {
    while (!q.empty()) q.pop();
    q.push(k);
    dist[k][k] = 0;
    while (!q.empty()) {
      fr = q.front();
      q.pop();
      flag[fr][fr] = false;
      for (int i = 0; i < v[fr].size(); i++) {
        if (flag[k][v[fr][i]]) {
          flag[k][v[fr][i]] = false;
          dist[k][v[fr][i]] = dist[k][fr] + 1;
          q.push(v[fr][i]);
        }
      }
    }
  }
  int s1, t1, l1, s2, t2, l2, ans = -1;
  scanf("%d %d %d", &s1, &t1, &l1);
  scanf("%d %d %d", &s2, &t2, &l2);
  for (int i = 1; i < n; i++) {
    for (int j = i + 1; j <= n; j++) {
      k1 = min(dist[s1][i] + dist[i][j] + dist[j][t1],
               dist[s1][j] + dist[i][j] + dist[i][t1]);
      k2 = min(dist[s2][i] + dist[i][j] + dist[j][t2],
               dist[s2][j] + dist[i][j] + dist[i][t2]);
      if (k1 <= l1 && k2 <= l2) {
        ans = max(ans, m - k1 - k2 + dist[i][j]);
      }
    }
  }
  if (dist[s1][t1] <= l1 && dist[s2][t2] <= l2) {
    ans = max(ans, m - dist[s1][t1] - dist[s2][t2]);
  }
  printf("%d\n", ans);
}
