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| #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 2e5 + 50, lg = (int)(log2(maxn)) + 1;
int n, m;
int tot, head[maxn], nxt[maxn << 1], ver[maxn << 1];
int d[maxn], f[maxn][lg];
ll s[maxn];
queue<int> q;
void add(int x, int y) { ver[++tot] = y, nxt[tot] = head[x], head[x] = tot; }
void bfs() {
d[1] = 1, q.push(1);
while (!q.empty()) {
int x = q.front();
q.pop();
for (int i = head[x]; i; i = nxt[i]) {
int y = ver[i];
if (d[y]) continue;
d[y] = d[x] + 1;
q.push(y);
f[y][0] = x;
for (int j = 1; j < lg; ++j) f[y][j] = f[f[y][j - 1]][j - 1];
}
}
}
int lca(int x, int y) {
if (d[x] < d[y]) swap(x, y);
for (int i = lg - 1; i >= 0; --i) {
if (d[f[x][i]] >= d[y]) x = f[x][i];
}
if (x == y) return x;
for (int i = lg - 1; i >= 0; --i) {
if (f[x][i] != f[y][i]) x = f[x][i], y = f[y][i];
}
return f[x][0];
}
void dfs(int x, int f) {
for (int i = head[x]; i; i = nxt[i]) {
int y = ver[i];
if (y == f) continue;
dfs(y, x);
s[x] += s[y];
}
}
int main() {
scanf("%d%d", &n, &m);
int x, y;
for (int i = 1; i < n; ++i) {
scanf("%d%d", &x, &y);
add(x, y), add(y, x);
}
bfs();
for (int i = 1; i <= m; ++i) {
scanf("%d%d", &x, &y);
s[x] += 1, s[y] += 1, s[lca(x, y)] -= 2;
}
dfs(1, 0);
ll ans = 0;
for (int i = 2; i <= n; ++i) {
if (s[i] == 0)
ans += m;
else if (s[i] == 1)
ans += 1;
}
printf("%lld\n", ans);
return 0;
}
|
