#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;
const ll logn = 20;
ll n;
ll dp[maxn];
ll dist[maxn];
ll d_bfs[maxn];
ll pr[maxn];
ll wei[maxn];
ll d[5*maxn];
ll ps[5*maxn];
ll bup[logn+3][maxn];
ll timer= 0 ;
ll tin[maxn]; ll tout[maxn];
void push(ll v) {
if (ps[v]==0)return;
ps[v*2] += ps[v]; ps[v*2+1]+=ps[v];
d[v*2]+=ps[v]; d[v*2+1]+=ps[v];
ps[v] = 0;
}
void upd(ll v, ll l, ll r, ll sl, ll sr, ll x){
push(v);
if (sl <= l && r <= sr){
ps[v]+=x;
d[v]+=x;
push(v);
return;
}
else if (sr <= l || r <= sl){
return;
}push(v);
upd(v*2 ,l, (l+r)/2, sl, sr,x); upd(v*2+1, (l+r)/2, r, sl, sr, x);
d[v]=max(d[v*2],d[v*2+1]);
}
ll get_max(ll v, ll l, ll r, ll sl, ll sr){
push(v);
if (sl <= l &&r <= sr){
return d[v];
}
else if (sr <= l || r <= sl)return 0;
push(v);
return max(get_max(v*2, l, (l+r)/2, sl, sr),get_max(v*2+1, (l+r)/2, r, sl, sr));
}
void cntp(ll v, vector<vector<ll>>&g,ll p){
pr[v] = p;
if (p != -1){
dp[v] = dp[p]+1;
}
tin[v]=timer++;
for (auto u: g[v]) {
if (u != p){
cntp(u, g, v);
bup[0][u] = v;
}
}
tout[v]=timer++;
}
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;
set<pll> ee;
for (int i =0; i < n-1; i++){
ll u, v;
cin>>u>>v;
g[u].push_back(v);
g[v].push_back(u);
ee.insert({min(u,v),max(u,v)});
ll w; cin >> w;
edges.push_back({u, v, w});
}
if (n <= 100000000ll/q){
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;
}
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 {
ll root = 1;
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;
}
dfs(root, g);
for (int lg = 1; lg <= logn; lg++){
for (int i =1; i <= n;i++){
bup[lg][i] = bup[lg-1][bup[lg-1][i]];
}
}
for (int i =1; i<= n;i++){
upd(1, 0, timer, tin[i],tin[i]+1,dist[i]);
upd(1, 0, timer, tout[i], tout[i]+1, dist[i]);
}
ll last= 0;
multiset<pll> all;
for (auto u : g[root]){
all.insert({-get_max(1, 0, timer, tin[u], tout[u]+1), u});
}
for (int i = 0; i <q; i++){
ll dj, ej;
cin>>dj>>ej;
dj = (dj+last)%(n-1);
ej = (ej+last)%ww;
ll uu = edges[dj][0];
ll vv = edges[dj][1];
if (pr[uu]==vv) {
swap(uu,vv);
}
edges[dj][2] = ej;
ll prev_wei = wei[vv];
wei[vv] = ej;
ll changed = vv;
for (int up = logn; up >= 0; up--){
if (dp[bup[up][changed]]>=1){
changed = bup[up][changed];
}
}
all.erase({-get_max(1, 0, timer, tin[changed], tout[changed]+1), changed});
upd(1, 0, timer, tin[vv], tout[vv]+1, wei[vv]-prev_wei);
all.insert({-get_max(1, 0, timer, tin[changed], tout[changed]+1), changed});
ll ans1 = -all.begin()->first;
ll ans0 = 0;
if (all.size()>1){
auto h = *(all.begin().operator++());
ans0 = -h.first;
}
cout<<ans1+ans0<<endl;
last =ans1+ans0;
}
}
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int t1 = 1;
while (t1) solve1(), t1--;
}
