#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int n, q;
ll w;
vector<map<int, int>> adj;
vector<pair<int, int>> edges;
bool s3 = true;
void read() {
cin >> n >> q >> w;
adj.resize(n);
edges.resize(n - 1);
for (int i = 0; i < n - 1; ++i) {
int a, b;
ll c;
cin >> a >> b >> c;
--a; --b;
if (a != 0) s3 = false;
edges[i] = {a, b};
adj[a][b] = c;
adj[b][a] = c;
}
}
void solve3() {
vector<multiset<ll>::iterator> v(n - 1);
multiset<ll, greater<>> s;
for (int i = 0; i < n - 1; ++i) {
v[i] = s.insert(adj[edges[i].first][edges[i].second]);
}
ll last = 0;
while (q--) {
int dd;
ll ee;
cin >> dd >> ee;
int d = ((ll)dd + last) % (n - 1);
ll e = (ee + last) % w;
adj[edges[d].first][edges[d].second] = e;
adj[edges[d].second][edges[d].first] = e;
s.erase(v[d]);
v[d] = s.insert(e);
if (n == 2) {
last = *s.begin();
} else {
last = *s.begin() + *(++s.begin());
}
cout << last << '\n';
}
}
ll mxcost;
int far;
void dfs(int ver, int par, ll cost) {
if (cost > mxcost) {
mxcost = cost;
far = ver;
}
for (auto &[u, c] : adj[ver]) if (u != par) {
dfs(u, ver, cost + c);
}
}
ll diameter() {
mxcost = 0;
far = 0;
dfs(0, -1, 0);
mxcost = 0;
dfs(far, -1, 0);
return mxcost;
}
void solve() {
ll last = 0;
while (q--) {
int dd;
ll ee;
cin >> dd >> ee;
int d = ((ll)dd + last) % (n - 1);
ll e = (ee + last) % w;
adj[edges[d].first][edges[d].second] = e;
adj[edges[d].second][edges[d].first] = e;
last = diameter();
cout << last << '\n';
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
read();
if (s3) {
solve3();
} else {
solve();
}
return 0;
}
