// #pragma GCC optimize("O3,Ofast,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
using namespace std;
#define lli long long int
#define MP make_pair
#define pb push_back
#define REP(i,n) for(int i = 0; (i) < (n); (i)++)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
void fastio() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
}
const double EPS = 0.00001;
const int INF = 1e9+500;
const int N = 3e5+5;
const int ALPH = 26;
const int LGN = 25;
constexpr int MOD = 1e9+7;
int n,q,w;
vector<vector<array<int, 2> > > adj(N, vector<array<int, 2> >());
vector<array<int, 3> > edg(N);
vector<int> dist(N);
void dfs(int node, int par) {
for(auto c : adj[node]) {
if(c[0] == par) continue;
dist[c[0]] = dist[node] + edg[c[1]][2];
dfs(c[0], node);
}
}
int get_diam() {
dist[1] = 0;
dfs(1, 0);
int ind = 1;
for(int i = 1; i <= n; i++) {
if(dist[i] > dist[ind]) ind = i;
}
dist[ind] = 0;
dfs(ind, 0);
return *max_element(dist.begin(), dist.begin() + n + 1);
}
inline void solve() {
cin >> n >> q >> w;
edg.resize(n - 1);
REP(i, n - 1) {
cin >> edg[i][0] >> edg[i][1] >> edg[i][2];
adj[edg[i][0]].pb({edg[i][1], i});
adj[edg[i][1]].pb({edg[i][0], i});
}
int last = 0;
REP(z, q) {
int d, e;
cin >> d >> e;
d = (d + last) % (n - 1);
e = (e + last) % w;
edg[d][2] = e;
last = get_diam();
cout << last << "\n";
}
}
signed main() {
fastio();
int test = 1;
//cin>>test;
while(test--) {
solve();
}
}
