#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
const int maxn = 1e5;
struct edge {
int to, wei;
edge() : to(0), wei(0) {}
edge(int to_, int wei_) :
to(to_), wei(wei_) {}
};
int n, q, w;
vector<int> par_of;
vector<int> wei;
vector<int> best_dist;
vector<int> ans;
multiset<int> m;
void upd_ans(int cur) {
if(m.find(ans[cur]) != m.end()) {
m.erase(m.find(ans[cur]));
}
ans[cur] = wei[2 * cur] + best_dist[2 * cur] + wei[2 * cur + 1] + best_dist[2 * cur + 1];
m.insert(ans[cur]);
}
int query(int cur) {
int res = 0;
while(cur > 0) {
best_dist[cur] = max(best_dist[2 * cur] + wei[2 * cur], best_dist[2 * cur + 1] + wei[2 * cur + 1]);
upd_ans(cur);
cur /= 2;
}
res = *m.rbegin();
return res;
}
void calc_best_dist(int cur) {
if(cur > n) {
return;
}
calc_best_dist(2 * cur);
calc_best_dist(2 * cur + 1);
best_dist[cur] = max(best_dist[2 * cur] + wei[2 * cur], best_dist[2 * cur + 1] + wei[2 * cur + 1]);
}
void solve() {
cin >> n >> q >> w;
par_of.assign(n - 1, 0);
wei.assign(1 + 2 * n + 1, 0);
best_dist.assign(1 + 2 * n + 1, 0);
ans.assign(1 + n, 0);
for(int i = 0; i < n - 1; i++) {
int a, b, c;
cin >> a >> b >> c;
if(a > b) {
swap(a, b);
}
par_of[i] = b;
wei[b] = c;
}
calc_best_dist(1);
for(int i = 1; i <= n; i++) {
upd_ans(i);
}
int last = 0;
while(q--) {
int d, e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
// ----- changable -----
wei[par_of[d]] = e;
int result = query(par_of[d] / 2);
// ----- changable -----
cout << result << "\n";
last = result;
}
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
solve();
return 0;
}
