#include <bits/stdc++.h>
using namespace std;
#define pb push_back
const int maxn = 2e5;
int n, m;
vector<int> graph[1 + maxn];
int g, s, a, b;
vector<int> dg, ds, da, db;
vector<int> bfs(int start) {
vector<int> res(1 + n, -1);
res[start] = 0;
queue<int> q;
q.push(start);
while(!q.empty()) {
int cur = q.front();
q.pop();
for(int nei : graph[cur]) {
if(res[nei] == -1) {
res[nei] = res[cur] + 1;
q.push(nei);
}
}
}
return res;
}
void solve() {
cin >> n >> m;
cin >> g >> s >> a >> b;
for(int i = 0; i < m; i++) {
int x, y;
cin >> x >> y;
graph[x].pb(y);
graph[y].pb(x);
}
dg = bfs(g), ds = bfs(s), da = bfs(a), db = bfs(b);
if((da[s] < da[g]) || (db[s] < db[g])) {
cout << "-1\n";
return;
}
int add_a = da[s] - 1 - da[g], add_b = db[s] - 1 - db[g];
bool extra_case = true;
if(add_a != add_b) {
add_a++, add_b++;
extra_case = false;
}
int to_add = min(add_a, add_b);
if(!extra_case) {
cout << to_add << "\n";
return;
}
to_add++;
da[g] += to_add;
db[g] += to_add;
for(int i = 1; i <= n; i++) {
if(i != g) {
dg[i] += to_add;
}
}
int closest_g = n + 1, closest_s = n + 1;
if(da[s] != db[s] || da[g] != db[g]) {
//exit(1);
}
if(da[s] != da[g] || db[s] != db[g]) {
exit(1);
}
for(int cur = 1; cur <= n; cur++) {
/*int max_dab = max(da[cur], db[cur]), min_dab = min(da[cur], db[cur]);
if((max_dab + closest_g == max(da[g], db[g])) && (min_dab + closest_g == min(da[g], db[g]))) {
closest_g = min(closest_g, max_dab);
}
if((max_dab + closest_s == max(da[s], db[s]))) {
closest_s = min(closest_s, max_dab);
}*/
int max_dab = max(da[cur], db[cur]);
int min_dab = min(da[cur], db[cur]);
if(max_dab + dg[cur] == max(da[g], db[g])) {
if(min_dab + dg[cur] == min(da[g], db[g])) {
closest_g = min(closest_g, max_dab);
}
}
if(max_dab + ds[cur] == max(da[s], db[s])) {
if(min_dab + ds[cur] == min(da[s], db[s])) {
closest_s = min(closest_s, max_dab);
}
}
}
if(closest_s < closest_g) {
to_add--;
}
cout << to_add << "\n";
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
solve();
return 0;
}
