#include <bits/stdc++.h>
using namespace std;
#define int long long
#define sm (ss + se) / 2
#define time mytime
int time = -1;
int tree[400005];
int pend[400004];
vector<pair<int, int>> edge[100005];
int depth[100005];
int in[100005], out[100005];
void push(int i, int ss, int se) {
if (pend[i] != 0) {
tree[i] += pend[i];
if (ss != se) {
pend[i * 2] += pend[i];
pend[i * 2 + 1] += pend[i];
}
pend[i] = 0;
}
}
void upd(int l, int r, int val, int ss = 0, int se = 100000, int i = 1) {
push(i, ss, se);
if (ss > se or r < ss or l > se) return;
if (l <= ss and r >= se) {
pend[i] += val;
push(i, ss, se);
return;
}
upd(l, r, val, ss, sm, i * 2);
upd(l, r, val, sm + 1, se, i * 2 + 1);
tree[i] = max(tree[i * 2], tree[i * 2 + 1]);
}
int get(int l, int r, int ss = 0, int se = 100000, int i = 1) {
push(i, ss, se);
if (ss > se or ss > r or se < l) return 0;
if (ss >= l and se <= r) {
return tree[i];
}
return max(get(l, r, ss, sm, i * 2), get(l, r, sm + 1, se, i * 2 + 1));
}
// int get(int l, int r) {
// int ans = 0;
// for (int i = l; i <= r; ++i) ans = max(ans, tree[i]);
// return ans;
// }
// void upd(int l, int r, int val) {
// for (int i = l; i <= r; ++i) tree[i] += val;
// }
void rek(int cur, int prev = -1) {
++time;
in[cur] = time;
for (auto [i, w] : edge[cur]) {
if (i == prev) continue;
depth[i] = depth[cur] + w;
rek(i, cur);
}
out[cur] = time;
}
int getmaks(int i) {
int lo = 0, hi = edge[0].size();
int maks = get(in[0], out[0]);
while (lo <= hi) {
int mid = (lo + hi) / 2;
if (get(in[0], out[edge[0][mid].first]) == maks) {
hi = mid - 1;
} else lo = mid + 1;
}
int maks2 = 0;
if (lo) maks2 = max(maks2, get(in[0], out[edge[0][lo - 1].first]));
if (lo + 1 < edge[0].size()) maks2 = max(maks2, get(out[edge[0][lo + 1].first], out[0]));
return maks + maks2;
}
signed main() {
int n, q, w;
cin >> n >> q >> w;
vector<pair<pair<int, int>, int>> edges;
for (int i = 0; i < n - 1; ++i) {
int u, v, w;
cin >> u >> v >> w;
--u, --v;
edge[u].push_back({v, w});
edge[v].push_back({u, w});
edges.push_back({{u, v}, w});
}
rek(0);
for (int i = 0; i < n; ++i) {
// cout << depth[i] << ' ';
// upd(in[i], out[i], depth[i]);
for (auto [j, w] : edge[i]) {
if (in[j] < in[i]) continue;
// cout << in[j] << ' ' << out[j] << ' ' << w << endl;
upd(in[j], out[j], w);
}
}
multiset<int> all;
for (int i = 0; i < n; ++i) {
all.insert(getmaks(i));
}
// cout << endl;
int last = 0;
// cout << get(3, 3) << endl;
while (q--) {
int d, e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
// cout << "REal " << d << ' ' << e << endl;
auto prev = edges[d];
edges[d].second = e;
auto [u, v] = prev.first;
if (in[u] > in[v]) swap(u, v);
// cout << in[v] << ' ' << out[v] << ' ' << e - prev.second << endl;
upd(in[v], out[v], e - prev.second);
// cout << maks << endl;
// cout << maks + maks2 << endl;
last = getmaks(0);
cout << last << endl;
}
}
