func_code_string: #include <bits/stdc++.h>   using namespace std;   const int maxn = 150001;   struct BIT {     int bit[maxn];     BIT() { memset(bit, 0, sizeof(bit)); }     void add(int x, int v) {       for (x++; x < maxn; x += x & -x) bit[x] += v;     }     void add(int a, int b, int v) { add(a, 1), add(b + 1, -1); }     int qry(int x) {       int ret = 0;       for (x++; x; x -= x & -x) ret += bit[x];       return ret;     }   };   struct segTree {     int l, r;     segTree *left = 0, *right = 0;     int val = 0;     segTree(int a, int b) : l(a), r(b){};     void add(int x, int v) {       if (l == r) {         val += v;         return;       }       int mid = (l + r) / 2;       if (x <= mid) {         if (!left) left = new segTree(l, mid);         left->add(x, v);       } else {         if (!right) right = new segTree(mid + 1, r);         right->add(x, v);       }       val = (left ? left->val : 0) + (right ? right->val : 0);     }     void mrg(segTree *tre) {       if (!tre) return;       if (!left)         left = tre->left;       else if (tre->left)         left->mrg(tre->left);       if (!right)         right = tre->right;       else if (tre->right)         right->mrg(tre->right);       val += tre->val;       delete tre;     }     int qry(int a, int b) {       if (a <= l && r <= b) return val;       int ret = 0, mid = (l + r) / 2;       if (a <= mid && b >= l && left) ret += left->qry(a, b);       if (b > mid && a <= r && right) ret += right->qry(a, b);       return ret;     }     void clear() {       if (left) left->clear();       if (right) right->clear();       delete this;     }   };   const int w = 18;   int n, m, k;   int q[maxn][2];   int p[w][maxn];   int d[maxn], sz[maxn], h[maxn], l[maxn], r[maxn];   vector<int> graph[maxn], v[maxn], v2[maxn];   BIT bit;   segTree *tre[maxn];   int dfsh(int c) {     sz[c] = 1, h[c] = -1;     for (int i = 1; i < w; i++) {       p[i][c] = ~p[i - 1][c] ? p[i - 1][p[i - 1][c]] : -1;     }     for (int i : graph[c]) {       if (i == p[0][c]) continue;       p[0][i] = c;       d[i] = d[c] + 1;       sz[c] += dfsh(i);       if (!~h[c] || sz[i] > sz[h[c]]) h[c] = i;     }     return sz[c];   }   int dfsh2(int c) {     r[c] = l[c];     for (int i : graph[c]) {       if (i == p[0][c] || i == h[c]) continue;       l[i] = r[c] + 1;       r[c] = dfsh2(i);     }     if (~h[c]) {       l[h[c]] = r[c] + 1;       r[c] = dfsh2(h[c]);     }     return r[c];   }   int lft(int c, int x) {     for (int i = 0; i < w; i++) {       if (((x >> i) & 1) && ~c) c = p[i][c];     }     return c;   }   int lca(int x, int y) {     if (d[x] < d[y]) swap(x, y);     x = lft(x, d[x] - d[y]);     for (int i = w - 1; ~i; i--) {       if (p[i][x] != p[i][y]) x = p[i][x], y = p[i][y];     }     return x == y ? x : p[0][x];   }   long long dfs2(int c, int rt) {     long long ret = 0;     tre[c] = new segTree(0, n - 1);     for (int i : v2[c]) {       int dd = max(0, k + d[rt] - d[q[i][0]]);       int j = q[i][1];       if (d[j] - d[rt] >= dd) {         j = lft(j, d[j] - d[rt] - dd);         ret += tre[c]->qry(l[j], r[j]);       }       tre[c]->add(l[q[i][1]], 1);     }     for (int i : graph[c]) {       if (i == p[0][c] || (c == rt && i == h[c])) continue;       ret += dfs2(i, rt);       if (v2[c].size() < v2[i].size()) {         swap(v2[c], v2[i]);         swap(tre[c], tre[i]);       }       for (int it : v2[i]) {         int dd = max(0, k + d[rt] - d[c]);         int j = q[it][1];         if (d[j] - d[rt] >= dd) {           j = lft(j, d[j] - d[rt] - dd);           ret += tre[c]->qry(l[j], r[j]);         }         v2[c].push_back(it);       }       v2[i].clear();       tre[c]->mrg(tre[i]);     }     return ret;   }   long long dfs(int c) {     long long ret = 0;     for (int i : graph[c])       if (i != p[0][c]) ret += dfs(i);     for (int t = 0; t < 2; t++) {       for (int i : v[c]) ret += bit.qry(l[q[i][t]]);       for (int i : v[c]) {         int j = q[i][t];         if (d[j] - d[c] >= k) {           j = lft(j, d[j] - d[c] - k);           bit.add(l[j], r[j], 1);         }         if (!t) v2[q[i][t]].push_back(i);       }     }     ret += dfs2(c, c);     v2[c].clear();     tre[c]->clear();     return ret;   }   int main() {     ios::sync_with_stdio(0);     cin.tie(0);     cin >> n >> m >> k;     for (int i = 0; i < n - 1; i++) {       int u, v;       cin >> u >> v;       u--, v--;       graph[u].push_back(v);       graph[v].push_back(u);     }     p[0][0] = -1;     dfsh(0), dfsh2(0);     for (int i = 0; i < m; i++) {       cin >> q[i][0] >> q[i][1];       q[i][0]--, q[i][1]--;       if (l[q[i][0]] > l[q[i][1]]) swap(q[i][0], q[i][1]);       v[lca(q[i][0], q[i][1])].push_back(i);     }     cout << dfs(0) <<   n ;     return 0;   }   