#include<bits/stdc++.h>
#define NOT_STONKS ios::sync_with_stdio(false), cin.tie(0), cout.tie(0)
using namespace std;
const int maxn = 2e5 + 10; //4e6 + 10; //3e5 + 10;
const int mod = 1e9 + 7; //998244353;
typedef long long ll;
ll n, q, w, f[maxn], s[maxn], dis[maxn];
vector< pair<ll, ll> > adj[maxn];
pair<ll, ll> temp;
pair< pair<ll, ll>, ll > edge[maxn];
void dfs(int v, int par = -1) {
for (auto [ u, x ] : adj[v]) if (u != par) {
dfs(u, v);
if (par != -1) {
f[v] = f[u];
s[v] = s[u] + x;
}
}
if (adj[v].size() == 1 && par != -1)
f[v] = v;
}
void trav(int v, int par = -1) {
for (auto [ u, x ] : adj[v]) if (u != par) {
dis[u] = dis[v] + x;
temp = max(temp, { dis[u], u });
trav(u, v);
}
}
int main() {
NOT_STONKS;
cin >> n >> q >> w;
for (int i = 0; i < n - 1; i++) {
int u, v, x;
cin >> u >> v >> x;
edge[i] = { { u, v }, x };
adj[u].push_back({ v, x });
adj[v].push_back({ u, x });
}
ll last = 0;
if (adj[1].size() == n - 1) {
dfs(1);
multiset<ll> m;
for (auto [ u, _ ] : adj[1])
m.insert(s[u]);
while (q--) {
int d, e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
int E = max(edge[d].first.first, edge[d].first.second);
m.erase(m.find(s[E]));
s[E] = e;
m.insert(s[E]);
multiset<ll>::iterator it = m.begin();
last = *it;
it++;
last += *it;
cout << last << '\n';
}
} else {
while (q--) {
int d, e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
auto E = edge[d];
int id1 = find(adj[E.first.first].begin(), adj[E.first.first].end(), make_pair(E.first.second, E.second)) - adj[E.first.first].begin();
int id2 = find(adj[E.first.second].begin(), adj[E.first.second].end(), make_pair(E.first.first, E.second)) - adj[E.first.second].begin();
adj[E.first.first].erase(adj[E.first.first].begin() + id1);
adj[E.first.second].erase(adj[E.first.second].begin() + id2);
edge[d] = { E.first, e };
adj[E.first.first].push_back({ E.first.second, e });
adj[E.first.second].push_back({ E.first.first, e });
temp = { 0, 0 };
dis[1] = 0;
trav(1);
dis[temp.second] = 0;
trav(temp.second);
last = temp.first;
cout << last << '\n';
}
}
return 0;
}
