#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int, int>
int N, Q, W;
const int MAX_N = 1e5;
vector<unordered_map<int, int>> adj;
vector<int> group;
struct SegTree{
int len =1;
vector<int> lazy;
vector<vector<pii>> tr;
SegTree(int n){
while(len<n){
len*=2;
}
lazy.resize(2*len);
tr.resize(2*len);
}
void upd(int u){
vector<pii> candidats;
for(auto e: tr[u*2]){
candidats.push_back(e);
}
for(auto e: tr[u*2+1]){
candidats.push_back(e);
}
sort(candidats.begin(), candidats.end());
reverse(candidats.begin(), candidats.end());
tr[u].clear();
for(auto e: candidats){
if(tr[u].size() ==2){
break;
}
if(tr[u].size() == 0 || tr[u].back().second != e.second){
tr[u].push_back(e);
}
}
for(pii& e: tr[u]){
e.first += lazy[u];
}
}
void insert(int id,int gid, int v, int lt, int rt, int t){
if(lt==rt){
tr[t].push_back({v, gid});
}
else{
int mid =(lt+rt)/2;
if(id<=mid){
insert(id, gid, v, lt, mid, t*2);
}
else{
insert(id, gid, v, mid+1, rt, t*2+1);
}
upd(t);
}
}
void add(int l, int r,int v, int lt, int rt, int t){
if(r<lt|| rt<l){
return;
}
else if(l<=lt && rt<= r){
lazy[t]+= v;
for(pii& e: tr[t]){
e.first +=v;
}
}
else {
int mid = (lt+rt)/2;
add(l, r, v, lt, mid, t*2);
add(l, r, v, mid+1, rt, t*2+1);
upd(t);
}
}
int get(){
int res = tr[1][0].first;
if(tr[1].size()>1){
res += tr[1][1].first;
}
return res;
}
};
pii get_furthest(int u, int a){
pii res ={0, u};
for(auto e: adj[u]){
if(e.first!=a){
pii de = get_furthest(e.first, u);
de.first += e.second;
if(de.first>res.first){
res = de;
}
}
}
return res;
}
void euler_tour(int u, int a, vector<pii>& tour_t, int &t,vector<int>& dpth, int d, vector<bool>& leaf){
int nb_c= 0;
tour_t[u].first = t;
dpth[u] = d;
for(auto e: adj[u]){
if(e.first!=a){
nb_c++;
euler_tour(e.first, u, tour_t, t, dpth, d+e.second, leaf);
}
}
if(nb_c == 0){
leaf[u] = true;
t++;
}
tour_t[u].second = t;
}
void group_dfs(int u, int a, int gid){
group[u] = gid;
for(auto e: adj[u]){
if(e.first != a){
group_dfs(e.first, u, gid);
}
}
}
signed main(){
cin>>N>>Q>>W;
adj.resize(N);
group.resize(N);
vector<pii> edges;
for(int i = 0; i<N-1; i++){
int a, b, c;
cin>>a>>b>>c;
a--;b--;
adj[a][b] = c;
adj[b][a] = c;
edges.push_back({a, b});
}
int root =0;
vector<pii> tour_t(N);
vector<int> dpth(N);
vector<bool> leaf(N);
int tm = 0;
euler_tour(root, -1, tour_t, tm, dpth, 0, leaf);
int cg= 1;
for(auto e: adj[root]){
group_dfs(e.first, root, cg);
cg++;
}
SegTree tr(N);
for(int i = 0; i<N; i++){
if(leaf[i]){
tr.add(tour_t[i].first, tour_t[i].second-1, dpth[i], 0, N-1, 1);
tr.insert(tour_t[i].first,group[i], dpth[i], 0, N-1, 1);
}
}
int last= 0;
for(int i = 0; i<Q; i++){
int d, e;
cin>>d>>e;
d = (d+last)%(N-1);
e = (e +last)%W;
int a = edges[d].first;
int b= edges[d].second;
if(dpth[a]<dpth[b]){
swap(a, b);
}
int delta = e-adj[a][b];
adj[a][b] = e;
adj[b][a] =e;
//cout<<a<<" delta "<<delta<<endl;
tr.add(tour_t[a].first, tour_t[a].second-1,delta, 0, N-1, 1);
last = tr.get();
cout<<last<<endl;
}
}
