#include <bits/stdc++.h>
#define mp make_pair
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pii;
struct seggy {
vector<ll> tree;
vector<ll> lazy;
int n;
seggy(vector<ll> arr) {
n = arr.size();
tree.resize(n * 4, 0);
lazy.resize(n * 4, 0);
for (int i = 0; i < n; i++)
update(i, i, arr[i]);
}
void push(int idx, int l, int r) {
ll val = lazy[idx];
tree[idx] += val;
lazy[idx] = 0;
if (l != r) {
lazy[idx * 2] += val;
lazy[idx * 2 + 1] += val;
}
}
void update_h(int l, int r, int L, int R, int idx, ll val) {
push(idx, l, r);
if (r < L || l > R)
return;
if (l >= L and r <= R) {
lazy[idx] += val;
push(idx, l, r);
return;
}
int mid = (l + r) / 2;
update_h(l, mid, L, R, idx * 2, val);
update_h(mid + 1, r, L, R, idx * 2 + 1, val);
tree[idx] = max(tree[idx * 2], tree[idx * 2 + 1]);
}
void update(int l, int r, ll val) {
update_h(0, n - 1, l, r, 1, val);
}
ll query_h(int l, int r, int L, int R, int idx) {
push(idx, l, r);
if (r < L || l > R)
return 0;
if (l >= L and r <= R)
return tree[idx];
int mid = (l + r) / 2;
ll out = max(query_h(l, mid, L, R, idx * 2)
, query_h(mid + 1, r, L, R, idx * 2 + 1));
tree[idx] = max(tree[idx * 2], tree[idx * 2 + 1]);
return out;
}
ll query(int l, int r) {
return query_h(0, n - 1, l, r, 1);
}
};
vector<ll> dfs_arr_dist;
vector<int> num_children;
vector<int> dfs_arr_idx;
vector<int> par;
vector<vector<pii> > graph;
void dfs(int curr, ll weight) {
dfs_arr_idx[curr] = dfs_arr_dist.size();
dfs_arr_dist.push_back(weight);
ll my_num_child = 1;
for (pii s : graph[curr]) {
if (s.first == par[curr])
continue;
par[s.first] = curr;
dfs(s.first, weight + s.second);
my_num_child += num_children[s.first];
}
num_children[curr] = my_num_child;
}
ll get_subtree_val(const int s, seggy& dfs_seg) {
return dfs_seg.query(dfs_arr_idx[s],
dfs_arr_idx[s] + num_children[s] - 1);
}
pii get_range(const int s) {
return {dfs_arr_idx[s],
dfs_arr_idx[s] + num_children[s] - 1};
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int n, q; ll w;
cin >> n >> q >> w;
num_children.resize(n + 1, 0);
dfs_arr_idx.resize(n + 1, 0);
par.resize(n + 1, 0);
graph.resize(n + 1);
vector<pii> edges;
for (int i = 1; i < n; i++) {
int f, t, w;
cin >> f >> t >> w;
edges.push_back({f, t});
graph[f].push_back({t, w});
graph[t].push_back({f, w});
}
for (int i = 1; i <= n; i++)
sort(graph[i].begin(), graph[i].end());
dfs(1, 0);
seggy dfs_seg(dfs_arr_dist);
multiset<ll> dps;
vector<int> one_idxs;
vector<int> one_idxs2;
for (pii s : graph[1]) {
dps.insert(
get_subtree_val(s.first, dfs_seg));
one_idxs.push_back(dfs_arr_idx[s.first]);
one_idxs2.push_back(s.first);
}
sort(one_idxs.begin(), one_idxs.end());
ll last = 0;
while (q--) {
ll e, d;
cin >> d >> e;
d += last;
e += last;
d %= (n - 1);
e %= w;
pii myedge = edges[d]; // first guy is parent
if (par[myedge.second] != myedge.first)
swap(myedge.first, myedge.second);
int guy = myedge.second;
int idx_of_edge = lower_bound(
graph[guy].begin(),
graph[guy].end(),
pii(myedge.first, 0))
- graph[guy].begin();
ll change = e - graph[guy][idx_of_edge].second;
graph[guy][idx_of_edge].second = e;
// getting subtree
int my_idx = dfs_arr_idx[guy];
int subtree = one_idxs2[prev(upper_bound(one_idxs.begin(),
one_idxs.end(),
my_idx
)) - one_idxs.begin()];
// chaning val in multiset
ll curr_val = get_subtree_val(subtree, dfs_seg);
dps.erase(dps.lower_bound(curr_val));
// changing val in seg and adding back to mulitset
dfs_seg.update(get_range(guy).first, get_range(guy).second, change);
dps.insert(get_subtree_val(subtree, dfs_seg));
ll ans = *prev(dps.end());
if (dps.size() > 1) {
ans = max(ans, *prev(dps.end()) + *prev(prev(dps.end())));
}
cout << ans << "\n";
last = ans;
}
}
