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#include <algorithm>
#include <fstream>
#include <vector>
#include <cmath>
using namespace std;
int N, ans = 0, pre[50005], d[50005] = { 0 }, L[20][50005] = { 0 };
vector<int> G[50005];
void dfs(int u, int p) {
d[u] = d[p] + 1;
L[0][u] = p;
for (int i = 0; (1 << i) < N; i++) if (L[i][u]) L[i + 1][u] = L[i][L[i][u]];
for (int v : G[u]) if (v != p) dfs(v, u);
}
int lca(int u, int v) {
if (d[u] > d[v]) swap(u, v);
for (int i = log2(N); i >= 0; i--) if (d[v] - (1 << i) >= d[u]) v = L[i][v];
if (u == v) return u;
for (int i = log2(N); i >= 0; i--) if (L[i][u] && L[i][u] != L[i][v]) u = L[i][u], v = L[i][v];
return L[0][u];
}
void solve(int u, int p) {
for (int v : G[u]) {
if (v != p) {
solve(v, u);
pre[u] += pre[v];
}
}
ans = max(pre[u], ans);
}
int main() {
ifstream cin("maxflow.in");
ofstream cout("maxflow.out");
int K;
cin >> N >> K;
for (int i = 0; i < N - 1; i++) {
int x, y;
cin >> x >> y;
G[x].push_back(y);
G[y].push_back(x);
}
dfs(1, 0);
while (K--) {
int s, t;
cin >> s >> t;
pre[s]++, pre[t]++;
pre[L[0][lca(s, t)]]--, pre[lca(s, t)]--;
}
solve(1, 0);
cout << ans << endl;
}
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