#include <cstdio>
#include <vector>
using namespace std;
struct BIT {
    int n, t[2000010];
    void modify(int k, int x) {
        for (int i = k; i <= n; i += i & (-i)) {
            t[i] += x;
        }
    }
    int query(int k) {
        int ans = 0;
        for (int i = k; i >= 1; i -= i & (-i)) {
            ans += t[i];
        }
        return ans;
    }
} bt;
vector<int> ans;
int n, m, x, y, u, v;
vector<int> G[2000010];
vector<pair<int, int> > queries[2000010];
int fa[22][2000010], d[2000010], dfn[2000010], dfe[2000010], times;
void dfs(int u, int f = 0) {
    dfn[u] = ++times;
    fa[0][u] = f;
    d[u] = d[f] + 1;
    for (int v : G[u]) {
        if (v == f) continue;
        dfs(v, u);
    }
    dfe[u] = times;
}
void init() {
    for (int i = 1; i < 22; i++) {
        for (int j = 1; j <= n; j++) {
            fa[i][j] = fa[i - 1][fa[i - 1][j]];
        }
    }
}
int lca(int x, int y) {
    if (d[x] > d[y]) swap(x, y);
    for (int i = 21; i >= 0; i--) {
        if (d[fa[i][y]] >= d[x]) {
            y = fa[i][y];
        }
    }
    if (x == y) return x;
    for (int i = 21; i >= 0; i--) {
        if (fa[i][x] != fa[i][y]) {
            x = fa[i][x];
            y = fa[i][y];
        }
    }
    return fa[0][x];
}
void dfsxy(int u) {
    for (int v : G[u]) {
        if (v == fa[0][u]) continue;
        dfsxy(v);
    }
    for (int i = 0; i < queries[u].size(); i++) {
        int now = bt.query(dfn[queries[u][i].first]) + bt.query(dfn[queries[u][i].second]);
        if (now == 0) {
            ans.push_back(u);
            bt.modify(dfn[u], 1);
            bt.modify(dfe[u] + 1, -1);
            break;
        }
    }
}
int main() {
    scanf("%d", &n);
    bt.n = n;
    for (int i = 1; i < n; i++) {
        scanf("%d%d", &x, &y);
        G[x].push_back(y);
        G[y].push_back(x);
    }
    dfs(1);
    init();
    scanf("%d", &m);
    for (int i = 1; i <= m; i++) {
        scanf("%d%d", &x, &y);
        queries[lca(x, y)].push_back({x, y});
    }
    dfsxy(1);
    printf("%d\n", ans.size());
    for (int i = 0; i < ans.size(); i++) {
        printf("%d ", ans[i]);
    }
    return 0;
}