#include <bits/stdc++.h>
using namespace std;
signed main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n, q;
int64_t w, last = 0;
cin >> n >> q >> w;
vector<pair<int, int>> g[n];
int edga[n - 1], edgb[n - 1];
int64_t weight[n - 1];
for (int i = 0; i < n - 1; i++) {
cin >> edga[i] >> edgb[i] >> weight[i];
g[--edga[i]].push_back({--edgb[i], i});
g[edgb[i]].push_back({edga[i], i});
}
if (n < 5001) {
const function<pair<int64_t, int>(int, int)> dfs = [&](int u, int p) {
pair ans{0LL, u};
for (auto &[v, e] : g[u]) {
if (v == p) continue;
pair p = dfs(v, u);
ans = max(ans, {p.first + weight[e], p.second});
}
return ans;
};
while (q--) {
int d;
int64_t e;
cin >> d >> e;
weight[d = (d + last) % (n - 1)] = e = (e + last) % w;
cout << (last = dfs(dfs(0, 0).second, -1).first) << '\n';
}
return 0;
}
multiset<int64_t> lens(weight, weight + n - 1);
lens.insert(0);
while (q--) {
int d;
int64_t e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
lens.erase(lens.find(weight[d]));
lens.insert(weight[d] = e);
cout << (last = *lens.rbegin() + *next(lens.rbegin())) << '\n';
}
}
