#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<ll> v;
typedef vector<v> vv;
typedef vector<vv> vvv;
typedef pair<ll, ll> p;
typedef vector<p> vp;
typedef vector<vp> vvp;
typedef vector<vvp> vvvp;
typedef pair<ll, p> tri;
typedef vector<tri> vtri;
typedef vector<vtri> vvtri;
typedef vector<vvtri> vvvtri;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<vvb> vvvb;
#define f first
#define s second
#define pb push_back
#define eb emplace_back
#define all(v) (v).begin(),(v).end()
const ll INF = 1e18;
const ll mod = 1e9 + 7;
void findFurtherest(vvp &graph, v &weights, vp &res, ll i)
{
res[i] = p(0, i);
for (auto x : graph[i])
{
if (res[x.f].f == -1)
{
findFurtherest(graph, weights, res, x.f);
res[i] = max(res[i], p(res[x.f].f + weights[x.s], res[x.f].s));
}
}
}
void getRes(vvp &graph, v &weights, vp &furtherest, ll i, vb &visited, v &res)
{
if (visited[i]) return;
visited[i] = true;
ll curMaxi = furtherest[i].f;
v children;
for (auto x : graph[i])
{
if (!visited[x.f])
{
children.pb(furtherest[x.f].f + weights[x.s]);
getRes(graph, weights, furtherest, x.f, visited, res);
}
}
sort(all(children),greater<ll>());
if (children.size() >= 2) curMaxi = max(curMaxi, children[0] + children[1]);
res[i] = curMaxi;
}
int main()
{
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
ll n, q, w;
cin >> n >> q >> w;
vtri edges(n - 1);
for (ll i = 0; i < n - 1; i++)
{
cin >> edges[i].s.f >> edges[i].s.s >> edges[i].f;
edges[i].s.f--; edges[i].s.s--;
}
v weight(n - 1);
for (ll i = 0; i < n - 1; i++) weight[i] = edges[i].f;
vvp graph(n);
for (ll i = 0; i < n - 1; i++)
{
graph[edges[i].s.f].eb(edges[i].s.s, i);
graph[edges[i].s.s].eb(edges[i].s.f, i);
}
v height(n);
v parent(n, -1);
stack<tri> dfs;
dfs.emplace(0, p(0,0));
while (!dfs.empty())
{
auto top = dfs.top();
dfs.pop();
if (parent[top.f] != -1) continue;
parent[top.f] = top.s.f; height[top.f] = top.s.s;
for (auto x : graph[top.f]) dfs.emplace(x.f, p(top.f, top.s.s + 1));
}
vvp dirGraph(n);
for (ll i =0 ; i < n; i++)
{
for (auto x : graph[i]) if (x.f != parent[i]) dirGraph[i].pb(x);
}
ll last = 0;
vp furtherest(n, p(-1,-1));
findFurtherest(graph, weight, furtherest, 0);
multiset<ll> values;
v res(n, -1);
vb visited(n, false);
getRes(graph, weight, furtherest, 0, visited, res);
multiset<ll,greater<ll>> reses;
for (ll x : res) reses.insert(x);
while (q--)
{
ll d, e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
weight[d] = e;
ll cur = edges[d].s.f;
if (height[edges[d].s.s] > height[cur]) cur = edges[d].s.s;
while (true)
{
furtherest[cur] = p(0, cur);
for (auto x : dirGraph[cur])
{
furtherest[cur] = max(furtherest[cur], p(furtherest[x.f].f + weight[x.s], furtherest[x.f].s));
}
reses.erase(reses.find(res[cur]));
ll curMaxi = furtherest[cur].f;
v children;
for (auto x : dirGraph[cur])
{
children.pb(furtherest[x.f].f + weight[x.s]);
}
sort(all(children),greater<ll>());
if (children.size() >= 2) curMaxi = max(curMaxi, children[0] + children[1]);
res[cur] = curMaxi;
reses.insert(curMaxi);
if (cur == 0) break;
cur = parent[cur];
}
vb visited(n, false);
last = *reses.begin();
cout << last << "\n";
}
return 0;
}
