#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
ll edge[100001], dp[100001], to_par[100001];
vector<pair<int, int>> graph[100001];
int par[100001], upper[100001], lower[100001];
multiset<ll> ms[100001], all;
void dfs(int node = 1, int parent = 0) {
par[node] = parent;
ms[node].insert(0);
for (pair<int, int> i : graph[node]) if (i.first != parent) {
upper[i.second] = node, lower[i.second] = i.first;
to_par[i.first] = i.second;
dfs(i.first, node);
ms[node].insert(dp[i.first] + edge[i.second]);
}
dp[node] = *ms[node].rbegin();
all.insert(dp[node] + *next(ms[node].rbegin()));
}
void propagate(int node, ll prv, ll curr) {
if (prv == curr) return;
ll par_prv = dp[node] + edge[to_par[node]];
all.erase(all.find(dp[node] + *next(ms[node].rbegin())));
ms[node].erase(ms[node].find(prv));
ms[node].insert(curr);
dp[node] = *ms[node].rbegin();
all.insert(dp[node] + *next(ms[node].rbegin()));
ll par_curr = dp[node] + edge[to_par[node]];
if (par[node]) propagate(par[node], par_prv, par_curr);
}
int main() {
cin.tie(0)->sync_with_stdio(0);
int n, q;
ll w;
cin >> n >> q >> w;
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v >> edge[i];
graph[u].push_back({v, i});
graph[v].push_back({u, i});
}
dfs();
ll last = 0;
while (q--) {
int d;
ll e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
propagate(upper[d], dp[lower[d]] + edge[d], dp[lower[d]] + e);
edge[d] = e;
last = *all.rbegin();
cout << last << '\n';
}
}
