#include <bits/stdc++.h>
using namespace std;
int n, m, K, C[151000], chk[151000];
vector<int> E[151000];
void Del(int a, int b) { E[a].erase(find(E[a].begin(), E[a].end(), b)); }
void DFS1(int a, int pp) {
  C[a] = 1;
  for (auto &x : E[a]) {
    if (x == pp) continue;
    DFS1(x, a);
    C[a] += C[x];
  }
}
int get_mid(int a, int pp, int c) {
  for (auto &x : E[a]) {
    if (x != pp && C[x] > c) return get_mid(x, a, c);
  }
  return a;
}
int Num[151000], Ed[151000], cnt, par[151000][18], Dep[151000], CC1[151000],
    CC2[151000], Rev[151000];
long long res;
void DFS2(int a, int pp, int dep) {
  CC1[a] = CC2[a] = 0;
  par[a][0] = pp;
  for (int i = 0; i < 17; i++) par[a][i + 1] = par[par[a][i]][i];
  Num[a] = ++cnt;
  Rev[cnt] = a;
  Dep[a] = dep;
  for (auto &x : E[a]) {
    if (x == pp) continue;
    DFS2(x, a, dep + 1);
  }
  Ed[a] = cnt;
}
int Up(int a, int d) {
  for (int i = 0; i < 18; i++)
    if ((d >> i) & 1) a = par[a][i];
  return a;
}
int LCA(int a, int b) {
  if (Dep[a] < Dep[b]) return LCA(b, a);
  a = Up(a, Dep[a] - Dep[b]);
  for (int i = 17; i >= 0; i--)
    if (par[a][i] != par[b][i]) a = par[a][i], b = par[b][i];
  if (a != b) a = par[a][0];
  return a;
}
void DFS3(int a, int pp) {
  res += 1ll * CC1[a] * CC2[a];
  for (auto &x : E[a]) {
    if (x == pp) continue;
    CC2[x] += CC2[a];
    DFS3(x, a);
  }
}
struct Node {
  int l, r, s;
} IT[151000 * 40];
vector<pair<int, int>> T;
int Root[151000 * 2], NC, BB[151000], EE[151000];
void Padd(int nd, int p, int b, int e, int x) {
  IT[nd] = IT[p];
  IT[nd].s++;
  if (b == e) return;
  int m = (b + e) >> 1;
  if (x <= m) {
    IT[nd].l = ++NC;
    Padd(IT[nd].l, IT[p].l, b, m, x);
  } else {
    IT[nd].r = ++NC;
    Padd(IT[nd].r, IT[p].r, m + 1, e, x);
  }
}
int Sum(int nd, int b, int e, int s, int l) {
  if (s > l) return 0;
  if (s <= b && e <= l) return IT[nd].s;
  int m = (b + e) >> 1, r = 0;
  if (s <= m) r += Sum(IT[nd].l, b, m, s, l);
  if (l > m) r += Sum(IT[nd].r, m + 1, e, s, l);
  return r;
}
long long rr;
int Get(int b, int e, int x, int d) {
  if (Dep[x] < d) return 0;
  x = Up(x, Dep[x] - d);
  return Sum(Root[e], 1, cnt, Num[x], Ed[x]) -
         Sum(Root[b - 1], 1, cnt, Num[x], Ed[x]);
}
void DFS4(int a, int pp) {
  vector<int> Ch;
  for (auto &x : E[a]) {
    if (x == pp) continue;
    DFS4(x, a);
    Ch.push_back(x);
  }
  BB[a] =
      lower_bound(T.begin(), T.end(), pair<int, int>(Num[a], 0)) - T.begin();
  BB[a]++;
  EE[a] = lower_bound(T.begin(), T.end(), pair<int, int>(Num[a] + 1, 0)) -
          T.begin();
  int i, d = max(0, K - Dep[a]);
  for (i = BB[a]; i < EE[a]; i++) {
    int x = Rev[T[i - 1].second];
    rr += Get(i + 1, EE[a], x, d);
  }
  int pv = 0, Mx = EE[a] - BB[a];
  vector<pair<int, int>> TT;
  TT.push_back({BB[a], EE[a]});
  for (auto &t : Ch) {
    if (EE[t] - BB[t] > Mx) {
      Mx = EE[t] - BB[t];
      pv = TT.size();
    }
    TT.push_back({BB[t], EE[t]});
    EE[a] = EE[t];
  }
  int push_back = TT[pv].first, pe = TT[pv].second;
  for (i = pv - 1; i >= 0; i--) {
    for (int j = TT[i].second; j >= TT[i].first; j--) {
      int x = Rev[T[j - 1].second];
      rr += Get(push_back, pe, x, d);
    }
    push_back = TT[i].first;
  }
  for (i = pv + 1; i < TT.size(); i++) {
    for (int j = TT[i].first; j <= TT[i].second; j++) {
      int x = Rev[T[j - 1].second];
      rr += Get(push_back, pe, x, d);
    }
    pe = TT[i].second;
  }
}
void DnC(int a, vector<pair<int, int>> &V) {
  if (V.empty()) return;
  DFS1(a, 0);
  int m = get_mid(a, 0, C[a] / 2);
  cnt = 0;
  DFS2(m, 0, 0);
  T.clear();
  vector<pair<int, pair<int, int>>> TP;
  for (auto &t : V) {
    int x = t.first, y = t.second;
    int l = LCA(x, y);
    if (l == m) {
      if (Dep[x] + Dep[y] < K) continue;
      T.push_back({Num[x], Num[y]});
      T.push_back({Num[y], Num[x]});
      CC1[x]++, CC1[y]++;
    } else {
      TP.push_back({Num[l], t});
      if (Dep[x] - Dep[l] >= K) {
        CC2[Up(x, Dep[x] - Dep[l] - K)]++;
      }
      if (Dep[l] <= Dep[y] - K) {
        CC2[Up(y, Dep[y] - Dep[l] - K)]++;
      }
    }
  }
  DFS3(m, 0);
  sort(T.begin(), T.end());
  Root[0] = 0;
  NC = 0;
  for (int i = 0; i < T.size(); i++) {
    Root[i + 1] = ++NC;
    Padd(Root[i + 1], Root[i], 1, cnt, T[i].second);
  }
  rr = 0;
  DFS4(m, 0);
  res += rr / 2;
  for (auto &x : E[m]) Del(x, m);
  sort(TP.begin(), TP.end());
  int pv = 0;
  vector<int> TE(E[m].size());
  for (int i = 0; i < E[m].size(); i++) TE[i] = Ed[E[m][i]];
  for (int i = 0; i < E[m].size(); i++) {
    vector<pair<int, int>> U;
    while (pv < TP.size() && TP[pv].first <= TE[i]) {
      U.push_back(TP[pv].second);
      pv++;
    }
    DnC(E[m][i], U);
  }
}
int main() {
  int i, a, b;
  scanf("%d%d%d", &n, &m, &K);
  for (i = 1; i < n; i++) {
    scanf("%d%d", &a, &b);
    E[a].push_back(b);
    E[b].push_back(a);
  }
  vector<pair<int, int>> V;
  for (i = 0; i < m; i++) {
    scanf("%d%d", &a, &b);
    V.push_back({a, b});
  }
  DnC(1, V);
  printf("%lld\n", res);
}
