#include <bits/stdc++.h>
using namespace std;
#define int int64_t
struct seg {
int n;
vector<int> tree;
vector<int> lazy;
void push(int v) {
tree[v*2] += lazy[v];
tree[v*2+1] += lazy[v];
lazy[v*2] += lazy[v];
lazy[v*2+1] += lazy[v];
lazy[v] = 0;
}
int query(int v, int rl, int rr, int ql, int qr) {
if (ql > qr) {
return 0;
}
if (ql == rl && qr == rr) return tree[v];
push(v);
int rm = (rl + rr) / 2;
return max(query(v*2, rl, rm, ql, min(rm, qr)), query(v*2+1, rm+1, rr, max(rm+1, ql), qr));
}
void update(int v, int rl, int rr, int ql, int qr, int x) {
if (ql > qr) {
return;
}
if (ql == rl && qr == rr) {
tree[v] += x;
lazy[v] += x;
return;
}
push(v);
int rm = (rl + rr) / 2;
update(v*2, rl, rm, ql, min(rm, qr), x);
update(v*2+1, rm+1, rr, max(rm+1, ql), qr, x);
tree[v] = max(tree[v*2], tree[v*2+1]);
}
void init(int _n, vector<int> a) {
n = _n;
tree.assign(n*4, 0);
lazy.assign(n*4, 0);
// for (int i = 0; i<n; i++) {
// update(1, 0, n-1, i, i, a[i]);
// }
}
};
vector<vector<int>> graph;
vector<vector<int>> parent;
vector<vector<int>> Size;
vector<vector<int>> whichSubtree;
vector<vector<pair<int, int>>> prepost;
vector<int> centroidLevel;
struct tree {
int level;
int currCol = 0;
seg segtree;
vector<int> order;
set<int> verticies;
vector<int> children;
int dfs(int v, int p, int forbidden) {
verticies.insert(v);
prepost[level][v].first = order.size();
order.push_back(v);
parent[level][v] = p;
if (p!=-1) whichSubtree[level][v] = currCol;
int s = 1;
for (int i: graph[v]) {
if (i == p || centroidLevel[i]!=-1) continue;
s += dfs(i, v, forbidden);
if (p==-1) {
children.push_back(i);
currCol++;
}
}
Size[level][v] = s;
prepost[level][v].second = order.size()-1;
return s;
}
bool isCentroid(int v, int p, int forbidden) {
int s = 1;
for (int i: graph[v]) {
if (i == p || centroidLevel[i]!=-1) continue;
if (Size[level][i] > (int)verticies.size()/2) return 0;
s += Size[level][i];
}
return (int)verticies.size()-s <= (int)verticies.size()/2;
}
int findCentroid(int v, int p, int forbidden) {
if (isCentroid(v, p, forbidden)) return v;
int biggest=0;
int indBiggest=-1;
for (int i: graph[v]) {
if (i == p || centroidLevel[i]!=-1) continue;
if (Size[level][i] > biggest) {
biggest = Size[level][i];
indBiggest = i;
}
}
// cerr << v << ": ";
// for (int i: verticies) cerr << i << " ";
// cerr << "\n";
assert(indBiggest!=-1);
return findCentroid(indBiggest, v, forbidden);
}
bool isParent(int p, int v) {
return (parent[level][v] == p);
}
set<pair<int, int>> bestInChild;
void updateEdge(int u, int v, int x) {
if (verticies.count(u)==0 || verticies.count(v)==0) return;
if (!isParent(u, v)) swap(u, v);
int child = whichSubtree[level][v];
pair<int, int> rangeChild = prepost[level][children[child]];
bestInChild.erase({segtree.query(1, 0, segtree.n-1, rangeChild.first, rangeChild.second), child});
pair<int, int> rangeUpdate = prepost[level][v];
segtree.update(1, 0, segtree.n-1, rangeUpdate.first, rangeUpdate.second, x);
bestInChild.insert({segtree.query(1, 0, segtree.n-1, rangeChild.first, rangeChild.second), child});
}
int getDiam() {
if (bestInChild.empty()) return 0;
if (bestInChild.size()==1) return (*bestInChild.rbegin()).first;
return (*bestInChild.rbegin()).first + (*next(bestInChild.rbegin())).first;
}
pair<int, vector<int>> init(int v, int _level, int forbidden) {
level = _level;
currCol = 0;
order.clear();
dfs(v, -1, forbidden);
int centroid = findCentroid(v, -1, forbidden);
currCol = 0;
order.clear();
verticies.clear();
children.clear();
dfs(centroid, -1, forbidden);
segtree.init(order.size(), vector<int>());
for (int i = 0; i<(int)children.size(); i++) {
auto range = prepost[level][children[i]];
bestInChild.insert({segtree.query(1, 0, segtree.n-1, range.first, range.second), i});
}
return {centroid, children};
}
};
int N, Q, W;
vector<tree> trees;
vector<vector<int>> inTrees;
set<pair<int, int>> allDiams; // len, treeInd
void makeTrees() {
queue<array<int, 3>> q; // centroid, level, parent;
q.push({0, 0, -1});
while (q.size()) {
tree x;
auto newComps = x.init(q.front()[0], q.front()[1], q.front()[2]);
centroidLevel[newComps.first] = q.front()[1];
// cerr << newComps.first << ": ";
for (int i: newComps.second) {
// cerr << i << " ";
q.push({i, q.front()[1]+1, newComps.first});
}
// cerr << "\n";
q.pop();
for (int i: x.verticies) inTrees[i].push_back(trees.size());
allDiams.insert({0, trees.size()});
trees.push_back(x);
// cerr << trees.back().level << "\n";
}
}
void updateEdge(int u, int v, int x) {
// cerr << u+1 << " " << v+1 << " " << x << "\n";
for (int i: inTrees[u]) {
allDiams.erase({trees[i].getDiam(), i});
trees[i].updateEdge(u, v, x);
allDiams.insert({trees[i].getDiam(), i});
}
}
int queryBest() {
return (*allDiams.rbegin()).first;
}
signed main() {
cin.tie(0);
ios_base::sync_with_stdio(0);
cin >> N >> Q >> W;
graph.resize(N);
inTrees.resize(N);
centroidLevel.assign(N, -1);
parent.assign(20, vector<int>(N));
Size.assign(20, vector<int>(N));
whichSubtree.assign(20, vector<int>(N));
prepost.assign(20, vector<pair<int, int>>(N));
vector<array<int,3>> edges(N-1);
for (int i = 0; i<N-1; i++) {
int a, b, c; cin >> a >> b >> c; a--; b--;
edges[i] = {a, b, c};
graph[a].push_back(b);
graph[b].push_back(a);
}
makeTrees();
for (auto i: edges) {
updateEdge(i[0], i[1], i[2]);
}
// cerr << "--------------\n";
int last = 0;
for (int i = 0; i<Q; i++) {
int _d, _e; cin >> _d >> _e;
int d = (_d+last)%(N-1);
int e = (_e+last)%(W);
int diff = e-edges[d][2];
// cerr << e << ": ";
updateEdge(edges[d][0], edges[d][1], diff);
edges[d][2] = e;
last = queryBest();
cout << last << "\n";
}
return 0;
}
