//雪花飄飄北風嘯嘯
//天地一片蒼茫
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << " is " << x << endl;
#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()
ll MAX(ll a){return a;}
ll MIN(ll a){return a;}
template<typename... Args>
ll MAX(ll a,Args... args){return max(a,MAX(args...));}
template<typename... Args>
ll MIN(ll a,Args... args){return min(a,MIN(args...));}
#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
struct node{
int s,e,m;
ii val;
ll lazy=0;
node *l,*r;
node (int _s,int _e){
s=_s,e=_e,m=s+e>>1;
val=ii(0,s);
if (s!=e){
l=new node(s,m);
r=new node(m+1,e);
}
}
void propo(){
if (lazy){
val.fi+=lazy;
if (s!=e){
l->lazy+=lazy;
r->lazy+=lazy;
}
lazy=0;
}
}
void update(int i,int j,ll k){
if (s==i && e==j) lazy+=k;
else{
if (j<=m) l->update(i,j,k);
else if (m<i) r->update(i,j,k);
else l->update(i,m,k),r->update(m+1,j,k);
l->propo(),r->propo();
val=max(l->val,r->val);
}
}
ii query(int i,int j){
propo();
if (s==i && e==j) return val;
else if (j<=m) return l->query(i,j);
else if (m<i) return r->query(i,j);
else return max(l->query(i,m),r->query(m+1,j));
}
};
struct mxnode{
int s,e,m;
ll val=0;
mxnode *l,*r;
mxnode (int _s,int _e){
s=_s,e=_e,m=s+e>>1;
if (s!=e){
l=new mxnode(s,m);
r=new mxnode(m+1,e);
}
}
void update(int i,ll j){
if (s==e) val=j;
else{
if (i<=m) l->update(i,j);
else r->update(i,j);
val=max(l->val,r->val);
}
}
} *mxroot=new mxnode(0,100005);
ll n,q,w;
vector<ii> al[100005];
bool used[100005];
int ss[100005];
void dfs_c(int i,int p){
ss[i]=1;
for (auto &it:al[i]){
if (it.fi==p || used[it.fi]) continue;
dfs_c(it.fi,i);
ss[i]+=ss[it.fi];
}
}
ll cw[100005];
vector<ii> range[100005];
vector<ii> subtree[100005];
vector<ii> pos[100005];
node* root[100005];
bool degen[100005];
int TIME;
ii dfs(int i,int p,int root){
ii r=ii(1e9,-1e9);
for (auto &it:al[i]){
if (it.fi==p || used[it.fi]) continue;
auto temp=dfs(it.fi,i,root);
if (i==root){
rep(x,temp.fi,temp.se+1) subtree[root].push_back(temp);
}
pos[it.se].push_back(ii(root,sz(range[root])));
range[root].push_back(temp);
r.fi=min(r.fi,temp.fi);
r.se=max(r.se,temp.se);
}
if (r==ii(1e9,-1e9)){
r=ii(TIME,TIME);
TIME++;
}
return r;
}
void centroid(int i){
//cout<<i<<" "<<sz<<endl;
dfs_c(i,-1);
int sz=ss[i];
int p=-1;
reloop:
for (auto &it:al[i]){
if (it.fi==p || used[it.fi]) continue;
if (ss[it.fi]>sz/2){
p=i;
i=it.fi;
goto reloop;
}
}
if (sz!=1){
TIME=1;
subtree[i].push_back(ii(1,1));
root[i]=new node(0,dfs(i,-1,i).se+1);
}
else{
degen[i]=true;
}
used[i]=true;
for (auto &it:al[i]){
if (it.fi==p || used[it.fi]) continue;
centroid(it.fi);
}
if (p!=-1) centroid(p);
}
void get(int i){
auto temp=root[i]->query(root[i]->s,root[i]->e);
mxroot->update(i,temp.fi+max(root[i]->query(root[i]->s,subtree[i][temp.se].fi-1),root[i]->query(subtree[i][temp.se].se+1,root[i]->e)).fi);
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n>>q>>w;
ll a,b,c;
rep(x,0,n-1){
cin>>a>>b>>c;
al[a].push_back(ii(b,x));
al[b].push_back(ii(a,x));
cw[x]=c;
}
centroid(1);
rep(x,0,n-1){
for (auto &it:pos[x]){
root[it.fi]->update(range[it.fi][it.se].fi,range[it.fi][it.se].se,cw[x]);
}
}
rep(x,1,n+1){
if (degen[x]) continue;
get(x);
}
ll last=0;
ll d,e;
while (q--){
cin>>d>>e;
d=(d+last)%(n-1);
e=(e+last)%w;
for (auto &it:pos[d]){
root[it.fi]->update(range[it.fi][it.se].fi,range[it.fi][it.se].se,e-cw[d]);
get(it.fi);
}
cw[d]=e;
last=mxroot->val;
cout<<last<<endl;
}
}
