#include <bits/stdc++.h>
using namespace std;
int n, L, m, head[1000005], cnt, root, sz[1000005], sum, mx;
long long t[1000005], ans;
struct edge {
  int to, next, cost;
} e[1000005 << 1];
struct dist {
  int len, dis;
  bool operator<(const dist &p) const { return dis < p.dis; }
} dis[1000005], q[1000005];
bool vis[1000005];
inline int read() {
  int x = 0, w = 1;
  char c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') w = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    x = x * 10 + c - '0';
    c = getchar();
  }
  return x * w;
}
int lowbit(int x) { return x & (-x); }
void add(int x, int y) {
  if (x == 0) return;
  for (int i = x; i <= n + 1; i += lowbit(i)) t[i] += y;
}
long long query(int x) {
  if (x <= 0) return 0;
  long long res = 0;
  for (int i = x; i; i -= lowbit(i)) res += t[i];
  return res;
}
inline void add(int u, int v, int w) {
  e[++cnt] = (edge){v, head[u], w};
  head[u] = cnt;
}
void fdrt(int u, int fa) {
  sz[u] = 1;
  int num = 0;
  for (int i = head[u]; i; i = e[i].next) {
    int v = e[i].to;
    if (v == fa || vis[v]) continue;
    fdrt(v, u);
    sz[u] += sz[v];
    num = max(num, sz[v]);
  }
  num = max(num, sum - sz[u]);
  if (mx > num) mx = num, root = u;
}
void gtds(int u, int fa) {
  q[++cnt] = dis[u];
  for (int i = head[u]; i; i = e[i].next) {
    int v = e[i].to;
    if (v == fa || vis[v]) continue;
    dis[v].len = dis[u].len + 1;
    dis[v].dis = dis[u].dis + e[i].cost;
    gtds(v, u);
  }
}
long long calc(int u, int len, int d) {
  cnt = 0;
  dis[u].len = len, dis[u].dis = d;
  gtds(u, 0);
  sort(q + 1, q + cnt + 1);
  for (int i = 1; i <= cnt; i++) add(q[i].len + 1, 1);
  int l = 1, r = cnt;
  long long res = 0;
  while (l < r) {
    if (q[l].dis + q[r].dis <= m) {
      add(q[l].len + 1, -1);
      res += query(L - q[l].len + 1);
      l++;
    } else
      add(q[r].len + 1, -1), r--;
  }
  add(q[l].len + 1, -1);
  return res;
}
void solve(int u) {
  ans += calc(u, 0, 0);
  vis[u] = 1;
  for (int i = head[u]; i; i = e[i].next) {
    int v = e[i].to;
    if (vis[v]) continue;
    ans -= calc(v, 1, e[i].cost);
    sum = mx = sz[v];
    fdrt(v, 0);
    solve(root);
  }
}
int main() {
  n = read();
  L = read();
  m = read();
  for (int i = 2; i <= n; i++) {
    int u = read(), w = read();
    add(u, i, w);
    add(i, u, w);
  }
  sum = mx = n;
  fdrt(1, 0);
  solve(root);
  printf("%I64d\n", ans);
  return 0;
}
