#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
using Edge = pair<ll, pll>;
#define fi first
#define se second
const int maxN = 1e5 + 5;
ll n, q, w;
set<pll> adj[maxN];
vector<Edge> edges;
vector<ll> dist;
void dfs(ll cur, ll par, ll cdist) {
dist[cur] = cdist;
for (auto &[nxt, w] : adj[cur]) {
if (nxt == par) continue;
dfs(nxt, cur, cdist+w);
}
}
ll solve() {
dist.assign(n+1, 0);
dfs(1, 0, 0);
ll e1 = -1, mx = -1;
for (ll i = 1; i <= n; i++) {
if (dist[i] > mx) {
mx = dist[i];
e1 = i;
}
}
dist.assign(n+1, 0);
dfs(e1, 0, 0);
ll ret = 0;
for (ll i = 1; i <= n; i++) {
ret = max(ret, dist[i]);
}
return ret;
}
int main() {
scanf("%lld %lld %lld", &n, &q, &w);
for (ll a, b, c, i = 1; i < n; i++) {
scanf("%lld %lld %lld", &a, &b, &c);
adj[a].insert({b, c});
adj[b].insert({a, c});
edges.push_back({c, {a, b}});
}
ll last = 0;
for (ll d, e, i = 1; i <= q; i++) {
scanf("%lld %lld", &d, &e);
d = (d + last) % (n - 1);
e = (e + last) % w;
auto &[w, p] = edges[d];
adj[p.fi].erase({p.se, w});
adj[p.se].erase({p.fi, w});
edges[d].fi = e;
adj[p.fi].insert({p.se, e});
adj[p.se].insert({p.fi, e});
/*
for (ll i = 1; i <= n; i++) {
cout << i << ": ";
for (auto &[j, k] : adj[i]) {
cout << "{" << j << ", " << k << "} ";
}
cout << '\n';
}
*/
last = solve();
printf("%lld\n", last);
}
}
