#include <bits/stdc++.h>

struct Edge {
  int a, b;
  int64_t c;
};
void solve1(int n, int q, int64_t w) {
  std::vector<Edge> e;
  std::vector<std::vector<std::pair<int64_t, int>>> adj(n);
  for (int i = 0; i < n - 1; ++i) {
    int a, b;
    int64_t c;
    std::cin >> a >> b >> c;
    a--;
    b--;
    adj[a].emplace_back(c, b);
    adj[b].emplace_back(c, a);
    e.push_back(Edge{a, b, c});
  }
  auto modify = [&](int d, int64_t c) {
    auto [a, b, _] = e[d];
    for (auto &[cost, i] : adj[a]) {
      if (i == b) {
        cost = c;
        break;
      }
    }
    for (auto &[cost, i] : adj[b]) {
      if (i == a) {
        cost = c;
        break;
      }
    }
  };
  auto diam = [&](auto &self, int node,
                  int par) -> std::pair<int64_t, int64_t> {
    int64_t ans = 0;
    std::set<int64_t, std::greater<int64_t>> s;
    for (auto [cost, i] : adj[node]) {
      if (i == par) {
        continue;
      }
      auto [d, t] = self(self, i, node);
      t += cost;
      ans = std::max(ans, d);
      s.insert(t);
    }
    int64_t ans2 = 0;
    if (!s.empty()) {
      ans2 += *s.begin();
    }
    if (s.size() >= 2) {
      ans2 += *std::next(s.begin());
    }
    return {std::max(ans, ans2), s.empty() ? 0 : *s.begin()};
  };
  int64_t last = 0;
  while (q--) {
    int d;
    int64_t c;
    std::cin >> d >> c;
    d = (d + last) % (n - 1);
    c = (c + last) % w;
    modify(d, c);
    last = diam(diam, 0, -1).first;
    std::cout << last << '\n';
  }
}
void solve2(int n, int q,
            std::vector<std::vector<std::pair<int64_t, int>>> &adj) {}

int main() {
  std::cin.tie(nullptr)->sync_with_stdio(false);

  int n, q;
  int64_t w;
  std::cin >> n >> q >> w;
  solve1(n, q, w);
}