#include <bits/stdc++.h>
using namespace std;
const int MAXN = 3005;
queue<int> q;
vector<int> G[MAXN];
int d[MAXN][MAXN];
bool vis[MAXN];
void bfs(int s) {
  memset(vis, 0, sizeof(vis));
  vis[s] = true;
  d[s][s] = 0;
  q.push(s);
  while (!q.empty()) {
    int u = q.front();
    q.pop();
    for (int i = 0; i < G[u].size(); i++) {
      int v = G[u][i];
      if (!vis[v]) {
        vis[v] = true;
        d[s][v] = d[s][u] + 1;
        q.push(v);
      }
    }
  }
}
int main() {
  int n, m, s1, t1, l1, s2, t2, l2;
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    G[a].push_back(b);
    G[b].push_back(a);
  }
  scanf("%d%d%d%d%d%d", &s1, &t1, &l1, &s2, &t2, &l2);
  for (int i = 1; i <= n; i++) bfs(i);
  if (d[s1][t1] > l1 || d[s2][t2] > l2) {
    printf("-1");
    return 0;
  }
  int ans = max(0, m - d[s1][t1] - d[s2][t2]);
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= n; j++) {
      int d1 = d[s1][i] + d[i][j] + d[j][t1],
          d2 = min(d[s2][i] + d[j][t2], d[s2][j] + d[i][t2]) + d[i][j];
      if (d1 <= l1 && d2 <= l2) ans = max(ans, m - d1 - d2 + d[i][j]);
    }
  printf("%d", ans);
  return 0;
}
