// XD XD
#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define el cout << "\n";
using namespace std;
using ll = long long;
const int MAXN = 5000 + 7;
const int MAXK = 2000 + 7;
const int MOD = 1e9 + 7;
const int INF = 1e9 + 7;
const ll LLINF = 1e18 + 7;
template <typename T>
bool ckmin(T& a, T b) {
return a > b ? a = b, true : false;
}
template <typename T>
bool ckmax(T& a, T b) {
return a < b ? a = b, true : false;
}
int n, m, k;
int a[MAXK], b[MAXK];
int bdist[MAXK], bways[MAXK];
int dist[MAXN], ways[MAXN];
vector<int> adj[MAXN];
queue<int> q;
void bfs(int u) {
for (int i = 1; i <= n; i++) {
dist[i] = INF;
ways[i] = 0;
}
q = {};
dist[u] = 0;
ways[u] = 1;
q.push(u);
while (q.size()) {
int u = q.front();
q.pop();
for (int v : adj[u]) {
if (dist[v] > dist[u] + 1) {
dist[v] = dist[u] + 1;
ways[v] = ways[u];
q.push(v);
} else if (dist[v] == dist[u] + 1) {
ways[v] += ways[u];
}
}
}
}
void solve(int id) {
// cout << "Case " << id << ": ";
cin >> n >> m;
for (int i = 1; i <= m; i++) {
int u, v;
cin >> u >> v;
u++;
v++;
adj[u].push_back(v);
adj[v].push_back(u);
}
cin >> k;
for (int i = 1; i <= k; i++) {
cin >> a[i] >> b[i];
a[i]++;
b[i]++;
}
for (int i = 1; i <= k; i++) {
bfs(a[i]);
bdist[i] = dist[b[i]];
bways[i] = ways[b[i]];
}
double expv = -INF;
int ans = 0;
for (int i = 1; i <= n; i++) {
double expi = 0;
bfs(i);
for (int j = 1; j <= k; j++) {
int tot = dist[a[j]] + dist[b[j]];
if (tot == bdist[j]) {
expi += 1.0 * (ways[a[j]] * ways[b[j]]) / bways[j];
}
}
if (ckmax(expv, expi)) {
ans = i;
}
}
cout << ans - 1 << "\n";
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int T = 1;
// cin >> T;
for (int i = 1; i <= T; i++) {
solve(i);
}
return 0;
}
