#include<bits/stdc++.h>
using namespace std;
const int MAXN=2e5+5;
struct edge
{
long long nex,pos,val;
};
struct node
{
long long ans,mnpref,mxsuff,fpref,fsuff,fsum,sum;
};
node merge(node a,node b)
{
node c;
c.ans=max(max(a.ans,b.ans),max(-a.mnpref+b.fsuff,a.fpref+b.mxsuff));
c.mnpref=min(b.mnpref,b.sum+a.mnpref);
c.mxsuff=max(a.mxsuff,a.sum+b.mxsuff);
c.fsum=max(-a.sum+b.sum,max(-a.sum+b.fsum,a.fsum+b.sum));
c.fpref=max(-a.mnpref+b.fsum,max(b.fpref,b.sum+a.fpref));
c.fsuff=max(b.mxsuff+a.fsum,max(a.fsuff,-a.sum+b.fsuff));
c.sum=a.sum+b.sum;
return c;
}
node seg[MAXN*4];
void update(int l,int r,int i,long long val,int pos)
{
if(i<l||r<i) return ;
if(l==r)
{
seg[pos]={abs(val),val,val,abs(val),abs(val),abs(val),val};
return ;
}
int mid=(l+r)/2;
update(l,mid,i,val,pos*2);
update(mid+1,r,i,val,pos*2+1);
seg[pos]=merge(seg[pos*2],seg[pos*2+1]);
}
vector<edge> ds[MAXN];
int L[MAXN],R[MAXN],pos[MAXN],tdfs=0;
long long len[MAXN];
void dfs(int i,int pre)
{
L[i]=++tdfs;
for(auto v:ds[i]) if(v.nex!=pre)
{
pos[v.pos]=v.nex;
dfs(v.nex,i);
}
R[i]=++tdfs;
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n,q;
long long w;
cin>>n>>q>>w;
for(int i=1;i<n;i++)
{
long long l,r,v;
cin>>l>>r>>v;
ds[l].push_back({r,i,v}),ds[r].push_back({l,i,v});
len[i]=v;
}
dfs(1,1);
for(int i=1;i<n;i++)
{
update(1,n*2,L[pos[i]],len[i],1);
update(1,n*2,R[pos[i]],-len[i],1);
}
long long last=0;
while(q--)
{
long long d,e;
cin>>d>>e;
d=(d+last)%(n-1)+1,len[d]=e=(e+last)%w;
update(1,n*2,L[pos[d]],e,1);
update(1,n*2,R[pos[d]],-e,1);
cout<<(last=seg[1].ans)<<"\n";
}
}
