//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define f first
#define s second
#define all(x) x.begin(),x.end()
#define _ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int dx[4]={0,0,1,-1};
int dy[4]={1,-1,0,0};
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
const int mxn=2e5+5;
vector<pair<int,ll>> adj[mxn];
int ord[mxn];
int st[mxn];
int en[mxn];
ll depth[mxn];
int timer=0;
struct node{
ll mn,mx,left,right,res;
};
vector<node> segtree(mxn*4);
vector<ll> lazy(mxn*4);
void dfs(int v,int p=0){
st[v]=timer;
ord[timer++]=v;
for(auto u:adj[v]){
if(u.f==p) continue;
depth[u.f]=depth[v]+u.s;
dfs(u.f,v);
ord[timer++]=v;
}
en[v]=timer-1;
}
node comb(node L,node R){
node ans;
ans.mn=min(L.mn,R.mn);
ans.mx=max(L.mx,R.mx);
ans.left=max({L.left,R.left,L.mx-R.mn*2});
ans.right=max({L.right,R.right,R.mx-L.mn*2});
ans.res=max({L.res,R.res,L.left+R.mx,L.mx+R.right});
return ans;
}
void push(int v){
ll val=lazy[v];
if(val==0) return;
segtree[v*2].mn+=val;
segtree[v*2].mx+=val;
segtree[v*2].left-=val;
segtree[v*2].right-=val;
segtree[v*2+1].mn+=val;
segtree[v*2+1].mx+=val;
segtree[v*2+1].left-=val;
segtree[v*2+1].right-=val;
lazy[v*2]+=val;
lazy[v*2+1]+=val;
lazy[v]=0;
}
void build(int l=0,int r=timer-1,int v=1){
if(l==r){
int x=ord[l];
segtree[v]={depth[x],depth[x],-depth[x],-depth[x],0};
return;
}
int mid=(l+r)/2;
build(l,mid,v*2);
build(mid+1,r,v*2+1);
segtree[v]=comb(segtree[v*2],segtree[v*2+1]);
}
void update(int tl,int tr,ll val,int l=0,int r=timer-1,int v=1){
if(r<tl or tr<l){
return;
}
if(tl<=l and r<=tr){
segtree[v].mn+=val;
segtree[v].mx+=val;
segtree[v].left-=val;
segtree[v].right-=val;
lazy[v]+=val;
return;
}
push(v);
int mid=(l+r)/2;
update(tl,min(mid,tr),val,l,mid,v*2);
update(max(mid+1,tl),tr,val,mid+1,r,v*2+1);
segtree[v]=comb(segtree[v*2],segtree[v*2+1]);
}
int main() {_
int n,q;
ll w;
cin>>n>>q>>w;
struct edge{
int a,b;
ll c;
};
vector<edge> E;
for(int i=0;i<n-1;i++){
int a,b;
ll c;
cin>>a>>b>>c;
adj[a].push_back({b,c});
adj[b].push_back({a,c});
E.push_back({a,b,c});
}
dfs(1);
build();
for(int i=0;i<n-1;i++){
if(depth[E[i].a]>depth[E[i].b]) swap(E[i].a,E[i].b);
}
ll last=0;
for(int i=0;i<q;i++){
ll d,e;
cin>>d>>e;
d=(d+last)%(n-1);
e=(e+last)%w;
int v=E[d].b;
update(st[v],en[v],e-E[d].c);
E[d].c=e;
last=segtree[1].res;
cout<<last<<'\n';
}
return 0;
}
//maybe its multiset not set
//yeeorz
//diaoborz
