#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define int long long
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define ppb pop_back
#define eb emplace_back
#define g0(a) get<0>(a)
#define g1(a) get<1>(a)
#define g2(a) get<2>(a)
#define g3(a) get<3>(a)
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
using db = double;
using ll = long long;
using ld = long double;
using ii = pair<int, int>;
using iii = tuple<int, int, int>;
using iiii = tuple<int, int, int, int>;
template<class key, class value = null_type, class cmp = less<key> >
using ordered_set = tree<key, value, cmp, rb_tree_tag, tree_order_statistics_node_update>;
int n, q, w, idx, a[100005], b[100005], c[100005], dep[100005], st[100005], ed[100005], seq[200005];
vector<ii> adj[100005];
void dfs(int n, int e = -1) {
idx++;
seq[idx] = n;
st[n] = ed[n] = idx;
for (auto [u, w] : adj[n]) if (u != e) {
dep[u] = dep[n] + w;
dfs(u, n);
idx++;
seq[idx] = n;
ed[n] = idx;
}
}
struct node {
node *left, *right;
int S, E, pv, val[6];
void combine() {
for (int k = 0; k < 6; k++)
val[k] = max(left->val[k], right->val[k]);
val[3] = max(val[3], left->val[0] + right->val[1]);
val[4] = max(val[4], left->val[1] + right->val[2]);
val[5] = max({val[5], left->val[3] + right->val[2], left->val[0] + right->val[4]});
}
node(int _s, int _e) : S(_s), E(_e), pv(0) {
if (S == E) {
val[0] = val[2] = dep[seq[S]];
val[1] = -2 * dep[seq[S]];
val[3] = val[4] = -dep[seq[S]];
val[5] = 0;
return;
}
int M = (S + E) >> 1;
left = new node(S, M);
right = new node(M + 1, E);
combine();
}
void prop() {
if (S == E || !pv) return;
for (auto i : {left, right}) {
for (int k = 0; k < 5; k++)
if (k == 0 || k == 2) i->val[k] += pv;
else if (k == 1) i->val[k] -= 2 * pv;
else if (k == 3 || k == 4) i->val[k] -= pv;
i->pv += pv;
}
pv = 0;
}
void upd(int l, int r, int v) {
if (l > E || r < S) return;
if (l <= S && E <= r) {
for (int k = 0; k < 5; k++)
if (k == 0 || k == 2) val[k] += v;
else if (k == 1) val[k] -= 2 * v;
else if (k == 3 || k == 4) val[k] -= v;
pv += v;
return;
}
prop();
left->upd(l, r, v);
right->upd(l, r, v);
combine();
}
} *root;
main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> q >> w;
for (int i = 1; i < n; i++) {
cin >> a[i] >> b[i] >> c[i];
adj[a[i]].eb(b[i], c[i]);
adj[b[i]].eb(a[i], c[i]);
}
dfs(1);
for (int i = 1; i < n; i++) {
if (dep[a[i]] > dep[b[i]]) swap(a[i], b[i]);
}
root = new node(1, idx);
for (int d, e, last = 0; q--; ) {
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
d++;
root->upd(st[b[d]], ed[b[d]], e - c[d]);
c[d] = e;
cout << (last = root->val[5]) << '\n';
}
}
