#include <bits/stdc++.h>
using namespace std;
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define sz(a) (int)(a).size()
#define all(a) (a).begin(), (a).end()
#define bit(s, i) (((s) >> (i)) & 1)
#define ii pair <int, int>
#define fi first
#define se second
#define ll long long
#define eb emplace_back
#define pb push_back
#define __builtin_popcount __builtin_popcountll
template <class X, class Y>
bool maximize(X &x, Y y) {
if(x < y) {
x = y;
return true;
}
return false;
}
template <class X, class Y>
bool minimize(X &x, Y y) {
if(x > y) {
x = y;
return true;
}
return false;
}
void solve();
int32_t main() {
#define task "test"
if(fopen(task".inp", "r")) {
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
cin.tie(0)->sync_with_stdio(0);
solve();
}
const int N=1e5+5;
int n,q,sz[N]; ll wmx,last,d[N];
bool del[N];
vector<pair<int,ll>> adj[N];
pair<ii,ll> edl[N];
multiset<ll> dia;
vector<ii> anc[N];
int getSize(int u, int p=-1){
sz[u]=1;
for(auto [v,w]:adj[u]) if(v!=p && !del[v]){
sz[u]+=getSize(v,u);
}
return sz[u];
}
int getCen(int u, int szAll, int p=-1){
for(auto [v,w]:adj[u]) if(v!=p && !del[v]){
if(sz[v]>szAll/2) return getCen(v,szAll,u);
}
return u;
}
struct Tree{
int root,num,Time;
vector<int> tout,up,near;
vector<ii> ver;
vector<ll> lz,st,valnear;
multiset<ll> road;
void dfs(int u, int p=-1){
int tin=++Time;
anc[u].eb(root,tin);
ver.eb(u,tin);
for(auto [v,w]:adj[u]) if(v!=p && !del[v]){
if(p==-1){
up[Time+1]=Time+1;
near.eb(Time+1);
}
else up[Time+1]=up[tin];
d[Time+1]=d[tin]+w;
dfs(v,u);
}
tout[tin]=Time;
}
void build(int id, int l, int r){
if(l==r){
st[id]=d[l];
return;
}
int mid=(l+r)>>1;
build(id<<1,l,mid);
build(id<<1|1,mid+1,r);
st[id]=max(st[id<<1],st[id<<1|1]);
}
void down(int id){
if(lz[id]==0) return;
st[id<<1]+=lz[id];
st[id<<1|1]+=lz[id];
lz[id<<1]+=lz[id];
lz[id<<1|1]+=lz[id];
lz[id]=0;
}
ll get(int u, int v, int id, int l, int r){
if(u>r||v<l) return 0;
if(u<=l&&r<=v) return st[id];
down(id);
int mid=(l+r)>>1;
return max(get(u,v,id<<1,l,mid),get(u,v,id<<1|1,mid+1,r));
}
void start(int r, int node){
root=r; num=node;
tout.resize(node+5);
lz.resize((node<<2)+5);
st.resize((node<<2)+5);
up.resize(node+5);
valnear.resize(node+5);
dfs(root);
build(1,1,node);
for(int i:near){
road.insert(valnear[i]=get(i,tout[i],1,1,node));
}
auto it2=prev(road.end());
if(sz(road)==1) dia.insert(*it2);
else dia.insert(*it2+*prev(it2));
sort(all(ver));
}
void add(int u, int v, ll val, int id, int l, int r){
if(u>r||v<l) return;
if(u<=l&&r<=v){
st[id]+=val;
lz[id]+=val;
return;
}
down(id);
int mid=(l+r)>>1;
add(u,v,val,id<<1,l,mid);
add(u,v,val,id<<1|1,mid+1,r);
st[id]=max(st[id<<1],st[id<<1|1]);
}
void upd(int v, ll w, int id){
int idu=id,idv;
auto it=lower_bound(all(ver),make_pair(v,0));
if(it==ver.end()||(*it).fi!=v) return;
idv=(*it).se;
if(idu>idv) swap(idu,idv);
auto it2=prev(road.end());
if(sz(road)==1) dia.erase(dia.find(*it2));
else dia.erase(dia.find(*it2+*prev(it2)));
road.erase(road.find(valnear[up[idv]]));
add(idv,tout[idv],w,1,1,num);
valnear[up[idv]]=get(up[idv],tout[up[idv]],1,1,num);
road.insert(valnear[up[idv]]);
ll val;
it2=prev(road.end());
if(sz(road)==1) dia.insert(val=*it2);
else dia.insert(val=*it2+*prev(it2));
}
} tree[N];
void decomp(int u){
int cen=getCen(u,getSize(u));
del[cen]=1;
if(sz[u]>1) tree[cen].start(cen,sz[u]);
for(auto [v,w]:adj[cen]) if(!del[v]) decomp(v);
}
void solve() {
cin>>n>>q>>wmx;
FOR(i,1,n-1){
int u,v; ll c; cin>>u>>v>>c;
edl[i]={{u,v},c};
adj[u].eb(v,c);
adj[v].eb(u,c);
}
decomp(1);
FOR(i,1,q){
int d; ll e; cin>>d>>e;
d=(d+last)%(n-1);
e=(e+last)%wmx;
ll change=e-edl[d+1].se;
edl[d+1].se=e;
for(auto [j,id]:anc[edl[d+1].fi.fi]){
tree[j].upd(edl[d+1].fi.se,change,id);
}
cout<<*prev(dia.end())<<'\n';
last=*prev(dia.end());
}
}
