#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));
}
}
}
ll getRes(vvp &graph, v &weights, vp &furtherest, ll i, vb &visited)
{
if (visited[i]) return 0;
visited[i] = true;
ll maxi = furtherest[i].f;
v children;
for (auto x : graph[i])
{
if (!visited[x.f])
{
children.pb(furtherest[x.f].f + weights[x.s]);
maxi = max(maxi, getRes(graph, weights, furtherest, x.f, visited));
}
}
sort(all(children),greater<ll>());
if (children.size() >= 2) maxi = max(maxi, children[0] + children[1]);
return maxi;
}
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);
}
ll last = 0;
vp furtherest(n, p(-1,-1));
findFurtherest(graph, weight, furtherest, 0);
while (q--)
{
ll d, e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
weight[d] = e;
furtherest = vp(n, p(-1,-1));
findFurtherest(graph, weight, furtherest, 0);
vb visited(n, false);
last = getRes(graph, weight, furtherest, 0, visited);
cout << last << "\n";
}
return 0;
}
