#ifndef local
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("O3")
#endif
#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;
using ll = long long;
#define int ll
using pii = pair<int, int>;
using pll = pair<ll,ll>;
using str = string;
using ld = long double;
using hash_map =gp_hash_table<int, int>;
using hash_set= gp_hash_table <int, null_type>;
auto sd = std::chrono::high_resolution_clock::now().time_since_epoch().count();
mt19937 rnd(sd);
typedef tree<ll, null_type, less<>, rb_tree_tag,
tree_order_statistics_node_update> ord_set;
const ll maxn = 3e5+8;
const ll inf = 2e18+7;
ll n;
ll dist[maxn];
ll d_bfs[maxn];
ll pr[maxn];
ll wei[maxn];
void cntp(ll v, vector<vector<ll>>&g,ll p){
pr[v] = p;
for (auto u: g[v]) {
if (u != p){
cntp(u, g, v);
}
}
}
void dfs(ll v, vector<vector<ll>>&g){
if (pr[v]!=-1)dist[v] = dist[pr[v]] +wei[v];
else dist[v] = 0;
for (auto u : g[v]){
if (u != pr[v]){
dfs(u, g);
}
}
}
void bfs(ll u, vector<vector<ll>> &g){
for(int i = 1; i <= n; i++){
d_bfs[i] = inf;
}
d_bfs[u] = 0;
queue<ll> q;
q.push(u);
ll w= 0;
while (!q.empty()){
u= q.front();
q.pop();
for (auto v : g[u]){
if (pr[u]==v) w = wei[u];
else w = wei[v];
if (d_bfs[v]>d_bfs[u]+w){
d_bfs[v]= d_bfs[u]+w;
q.push(v);
}
}
}
}
void solve1() {
ll q, ww;
cin >> n >> q>>ww;
vector<vector<ll>> g(n+1);
// 3 and 5g
// 1 and 2
// 4
vector<vector<ll>>edges;
for (int i =0; i < n-1; i++){
ll u, v;
cin>>u>>v;
g[u].push_back(v);
g[v].push_back(u);
ll w; cin >> w;
edges.push_back({u, v, w});
}
ll root = 1;
for (int i = 1; i <= n; i++){
if (g[i].size()>=2){
root = i;
break;
}
}cntp(root, g, -1);
for (auto t : edges){
ll u = t[0]; ll v = t[1];
ll w = t[2];
if (pr[u]==v){
wei[u] = w;
}
else wei[v] = w;
}
if (n <= 100000){
ll last= 0;
for (int j =0 ; j < q; j++){
ll dj, ej;
cin>>dj>>ej;
dj = (dj+last)%(n-1);
ej = (ej+last)%ww;
edges[dj][2] = ej;
if (edges[dj][0] == pr[edges[dj][1]]){
wei[edges[dj][1]] = ej;
}
else {
wei[edges[dj][0]] = ej;
}
dfs(root, g);
ll u1 =root;
ll w1 = 0;
for (int i = 1; i<= n;i++){
if (dist[i]>w1){
w1 = dist[i];
u1= i;
}
}
bfs(u1, g);
ll mx_ans = 0;
for (int i = 1; i <= n; i++){
mx_ans =max(mx_ans, d_bfs[i]);
}
last = mx_ans;
cout<<mx_ans<<endl;
}
}
// else if ()
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
#ifdef local
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
#endif
int t1 = 1;
while (t1) solve1(), t1--;
#ifdef local
printf_s("\n%.5f s", (double) clock() / CLOCKS_PER_SEC);
#endif
}
