#include<iostream>
#include<string>
#include<map>
#include <queue>
#include<vector>
using namespace std;
long n,m,s1,t1,l1,s2,t2,l2,p[100001]; vector <int> g[100001];
long d[5][100001];queue <int> q; bool used[1000001];
void bfs(int v,int ind){
     q.push(v); p[v]=-1;used[v]=1;
                     while(!q.empty()){
                                int w=q.front();
                                q.pop();
                                for (int k=0;k<g[w].size();++k){
                                    int t=g[w][k];
                                    if (!used[t]){
                                              used[t]=true;
                                              q.push(t);
                                              d[ind][t]=d[ind][w]+1;
                                              p[t]=w;
                                                  }
                                }
                                  }
     }
     vector <int> a,b;
int main(){
//freopen("input.txt","r",stdin);freopen("output.txt","w",stdout);
 cin>>n>>m;
 for (int k=1;k<=m;++k) {
     long a,b;
     cin>>a>>b;
     g[a].push_back(b);
     g[b].push_back(a);
 }
 cin>>s1>>t1>>l1>>s2>>t2>>l2;
 bfs(s1,0);
 long k=t1;
                                while (k>=1){
                                    a.push_back(k);
                                     k=p[k];
                                     }
 for (int k=0;k<=n;++k) used[k]=0;
 bfs(s2,1);
 k=t2;
    while (k>=1){
        //  cout<<k<<endl;
                                    b.push_back(k);
                                     k=p[k];
                                     }
   long z=d[0][t1]+d[1][t2];
   if (d[0][t1]>l1 || d[1][t2]>l2) z=1000000;
   if ((d[0][t1]==0  && s1!=t1)|| (s2!=t2&&d[1][t2]==0)) {
                   cout<<-1;
                   return 0;
                     }
  // cout<<z;return 0;
    long p1=d[1][s1]+d[0][t1];
    if (d[0][t1]>l1) p1+=10000000;
    long minx=1000000,j=-1;
     for (int k=0;k<=n;++k) used[k]=0;
    bfs(t2,2);
    for (int k=0;k<a.size();++k) {
         if (minx>d[2][a[k]]) j=a[k];
        minx=min(minx,d[2][a[k]]);}
        if (d[1][s1]+d[0][j]+d[2][j]<=l2 && j!=-1)
       z=min(z,p1+minx);
        p1=d[0][s2]+d[1][t2];
        if (d[1][t2]>l2) p1+=100000000;
         for (int k=0;k<=n;++k) used[k]=0;
        bfs(t1,3);
      minx=1000000,j=-1;
      for (int k=0;k<b.size();++k) {
         if (minx>d[3][b[k]]) j=b[k];
        minx=min(minx,d[3][b[k]]);}
      //  cout<<d[3][j];return 0;
        if (d[0][s2]+d[1][j]+d[3][j]<=l1 && j!=-1)
        z=min(z,p1+minx);
        if (m>=z) cout<<m-z; else cout<<-1;
  return 0;
}