#include <bits/stdc++.h>
using namespace std;
int n, k, ans, st[1000005][25], dep[1000005], diff[1000005], val[1000005];
vector <int> g[1000005];
void init(int u, int fa) {
dep[u] = dep[fa] + 1;
st[u][0] = fa;
for (int i = 1; i <= 20; i++) st[u][i] = st[st[u][i - 1]][i - 1];
for(int v : g[u]) if (v != fa) init(v, u);
}
int LCA(int x, int y) {
if (dep[x] < dep[y]) swap(x, y);
int dis = dep[x] - dep[y];
for (int i = 0; i <= 20; i++) if ((dis >> i) & 1) x = st[x][i];
if (x == y) return x;
for (int i = 20; i >= 0; i--) if (st[x][i] != st[y][i]) x = st[x][i], y = st[y][i];
return st[x][0];
}
void dfs(int u, int fa) {
val[u] = diff[u];
for (int v : g[u]) {
if (v == fa) continue;
dfs(v, u);
val[u] += val[v];
} ans = max(ans, val[u]);
}
int main() {
for (int i = 1; i < n; i++) {
int x, y;
cin >> x >> y;
g[x].push_back(y);
g[y].push_back(x);
} init(1, 0); while (k--) {
int u, v;
cin >> u >> v;
int lca = LCA(u, v);
diff[u] += 1, diff[v] += 1, diff[lca] -= 1, diff[st[lca][0]] -= 1;
} dfs(1, 0); cout << ans;
return 0;
}
