#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define pb push_back
#define pii pair<int,int>
typedef long long ll;
const int maxn=5e5+5;
const ll INF=1e18;
vector<vector<pii>> adj;
vector<int> w;
int n;
pii dijkstra(int s)
{
priority_queue<pii> q;
ll d[n+1];
for(int i=0;i<=n;i++)d[i]=INF;
d[s]=0;
q.push({0,s});
int v,t;
bool visited[n+1];
memset(visited,false,sizeof visited);
while(!q.empty())
{
t=-q.top().first;
v=q.top().second;
q.pop();
if(t!=d[v])continue;
visited[v]=true;
for(auto u:adj[v])
{
if(visited[u.first])continue;
ll len=t+w[u.second];
if(len<d[u.first])
{
d[u.first]=len;
q.push({-len,u.first});
}
}
}
ll odg=0,idx=-1;
for(int i=1;i<=n;i++)
{
if(d[i]>odg)
{
odg=d[i];
idx=i;
}
}
return {odg,idx};
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int q;
ll W;
cin>>n>>q>>W;
w.resize(n+1);
adj.resize(n+1);
ll a,b,c;
for(int i=1;i<n;i++)
{
cin>>a>>b>>c;
adj[a].pb({b,i});
adj[b].pb({a,i});
w[i]=c;
}
ll last=0,d,e;
if(n>5000||q>5000)
{
multiset<ll> s;
for(int i=1;i<=n-1;i++)s.insert(w[i]);
for(int i=0;i<q;i++)
{
cin>>d>>e;
d=(d+last)%(n-1)+1;
e=(e+last)%W;
s.erase(s.find(w[d]));
s.insert(e);
ll x=*(--s.end());
s.erase(s.find(x));
ll ans=x+(*(--s.end()));
s.insert(x);
cout<<ans<<endl;
last=ans;
w[d]=e;
}
}
for(int i=0;i<q;i++)
{
cin>>d>>e;
d=(d+last)%(n-1)+1;
e=(e+last)%W;
w[d]=e;
int v=dijkstra(1).second;
last=dijkstra(v).first;
cout<<last<<endl;
}
return 0;
}
