#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
typedef pair<int, int> ii;
const LL INF = 2e18;
const int N = 1e5 + 11;
vector<ii> adj[N];
bool is_c[N];
int totChild = 0;
int nChild[N];
int parCentroid[N];
void cal_child(int u, int p = 0) {
nChild[u] = 1;
for (auto [v, w] : adj[u])
if (!is_c[v] && v != p) {
cal_child(v, u);
nChild[u] += nChild[v];
}
}
int find_c(int u, int p = 0) {
for (auto [v, w] : adj[u])
if (v != p && !is_c[v] && nChild[v] > totChild / 2)
return find_c(v, u);
return u;
}
unordered_map<int, LL> dist;
struct Node {
LL val = 0, lazy = 0;
Node* l = nullptr, *r = nullptr;
Node(){}
};
Node* Seg[N];
void build(Node *cur, int l, int r) {
if (l == r) {
cur -> val = dist[l];
return;
}
cur -> l = new Node();
cur -> r = new Node();
int mi = (l + r) / 2;
build(cur -> l, l, mi);
build(cur -> r, mi + 1, r);
cur -> val = max(cur -> l -> val, cur -> r -> val);
}
void diffuse(Node *cur, int l, int r) {
if (cur -> lazy) {
cur -> val += cur -> lazy;
if (l != r) {
cur -> l -> lazy += cur -> lazy;
cur -> r -> lazy += cur -> lazy;
}
cur -> lazy = 0;
}
}
void upd(Node *cur, int l, int r, int L, int R, LL val) {
diffuse(cur, l, r);
if (r < L || R < l) return;
if (L <= l && r <= R) {
cur -> lazy += val;
diffuse(cur, l, r);
return;
}
int mi = (l + r) / 2;
upd(cur -> l, l, mi, L, R, val);
upd(cur -> r, mi + 1, r, L, R, val);
cur -> val = max(cur -> l -> val, cur -> r -> val);
}
LL query(Node *cur, int l, int r, int L, int R) {
diffuse(cur, l, r);
if (r < L || R < l) return 0LL;
if (L <= l && r <= R) return cur -> val;
int mi = (l + r) / 2;
LL val_l = query(cur -> l, l, mi, L, R);
LL val_r = query(cur -> r, mi + 1, r, L, R);
return max(val_l, val_r);
}
int cur_root;
unordered_map<int, int> top;
map<ii, int> st, ed;
multiset<LL> val_ms[N];
vector<pair<int, LL>> val_ord[N];
void dfs(int u, LL d = 0, int p = 0) {
st[ii(cur_root, u)] = ++top[cur_root];
dist[top[cur_root]] = d;
for (auto [v, w] : adj[u]) {
if (is_c[v] || v == p) continue;
dfs(v, d + w, u);
}
ed[ii(cur_root, u)] = top[cur_root];
}
LL sol[N];
multiset<LL> ans;
void prep(int root) {
cur_root = root;
Seg[root] = new Node();
dist[root] = 0;
dfs(root);
build(Seg[root], 1, top[root]);
for (auto [v, w] : adj[root]) {
if (is_c[v]) continue;
int l = st[ii(root, v)], r = ed[ii(root, v)];
LL val = query(Seg[root], 1, top[root], l, r);
val_ms[root].insert(val);
val_ord[root].emplace_back(l, val);
}
sort(val_ord[root].begin(), val_ord[root].end());
val_ms[root].insert(0); val_ms[root].insert(0);
val_ord[root].emplace_back(top[root] + 1, 0);
auto it = val_ms[root].rbegin();
LL v1 = *it; ++it; LL v2 = *it;
sol[root] = v1 + v2; ans.insert(sol[root]);
}
void centroid_decompose(int u, int p = 0) {
cal_child(u); totChild = nChild[u];
int c = find_c(u);
parCentroid[c] = p;
if (nChild[c] >= 2)
prep(c);
is_c[c] = true;
for (auto [v, w] : adj[c])
if (!is_c[v])
centroid_decompose(v, c);
}
void upd_edge(int root, int u1, int u2, LL inc) {
int u = ((st[ii(root, u1)] > st[ii(root, u2)]) ? u1 : u2);
upd(Seg[root], 1, top[root], st[ii(root, u)], ed[ii(root, u)], inc);
int p = upper_bound(val_ord[root].begin(), val_ord[root].end(), make_pair(st[ii(root, u)], INF)) - val_ord[root].begin() - 1;
int l = val_ord[root][p].first, r = val_ord[root][p + 1].first - 1;
LL old_val = val_ord[root][p].second;
LL new_val = query(Seg[root], 1, top[root], l, r);
val_ms[root].erase(val_ms[root].find(old_val));
val_ms[root].insert(new_val);
val_ord[root][p].second = new_val;
auto it = val_ms[root].rbegin();
LL v1 = *it; ++it; LL v2 = *it;
ans.erase(ans.find(sol[root]));
sol[root] = v1 + v2; ans.insert(sol[root]);
if (parCentroid[root])
upd_edge(parCentroid[root], u1, u2, inc);
}
int32_t main() {
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
int n, q; LL w;
cin >> n >> q >> w;
vector<LL> W(n);
vector<ii> edges;
for (int i = 0; i < n - 1; i++) {
int u, v; LL c;
cin >> u >> v >> c;
W[i] = c;
edges.emplace_back(u, v);
adj[u].emplace_back(v, c);
adj[v].emplace_back(u, c);
}
centroid_decompose(1);
int last = 0;
while (q--) {
int d; LL e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
LL dif = e - W[d]; W[d] = e;
auto [u, v] = edges[d];
if (top[u] < top[v]) swap(u, v);
upd_edge(u, u, v, dif);
last = *ans.rbegin();
cout << last << '\n';
}
}
