#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
const int M = 1e5 + 1;
struct node
{
int x, l, i;
};
int subt[M], st[M], en[M], par[M], nx[M], id[M], cnt[M], ind[M], rev[M], t, t1, n;
node seg[M*2];
vector<pair<int,int>> nei[M],nei1[M];
vector<node> seg1[M];
void push(int v,int lc,int rc)
{
seg[lc].x+=seg[v].l, seg[lc].l+=seg[v].l;
seg[rc].x+=seg[v].l, seg[rc].l+=seg[v].l;
seg[v].l=0;
}
node merge(node a, node b)
{
if (b.x>a.x) a=b;
a.l=0;
return a;
}
void modify(int l,int r,int x,int v=0,int s=0,int e=n)
{
if (l>=e or r<=s) return;
if (l<=s && e<=r)
{
if (s+1==e) seg[v].i=s;
seg[v].x+=x, seg[v].l+=x;
return;
}
int mid=(s+e)/2, lc=v+1, rc=v+(mid-s)*2;
push(v,lc,rc);
modify(l,r,x,lc,s,mid);
modify(l,r,x,rc,mid,e);
seg[v]=merge(seg[lc],seg[rc]);
}
node get(int l,int r,int v=0,int s=0,int e=n)
{
if (l>=e or r<=s) return {0,0,0};
if (l<=s && e<=r) return seg[v];
int mid=(s+e)/2, lc=v+1, rc=v+(mid-s)*2;
push(v,lc,rc);
return merge(get(l,r,lc,s,mid),get(l,r,rc,mid,e));
}
void push1(int v,int lc,int rc,int i)
{
seg1[i][lc].x+=seg1[i][v].l, seg1[i][lc].l+=seg1[i][v].l;
seg1[i][rc].x+=seg1[i][v].l, seg1[i][rc].l+=seg1[i][v].l;
seg1[i][v].l=0;
}
void mod(int l,int r,int x,int i,int v,int s,int e)
{
if (l>=e or r<=s) return;
if (l<=s && e<=r)
{
seg1[i][v].x+=x, seg1[i][v].l+=x;
return;
}
int mid=(s+e)/2, lc=v+1, rc=v+(mid-s)*2;
push1(v,lc,rc,i);
mod(l,r,x,i,lc,s,mid);
mod(l,r,x,i,rc,mid,e);
seg1[i][v]=merge(seg1[i][lc],seg1[i][rc]);
}
int get1(int l,int r,int i,int v,int s,int e)
{
if (l>=e or r<=s) return -M*3;
if (l<=s && e<=r) return seg1[i][v].x;
int mid=(s+e)/2, lc=v+1, rc=v+(mid-s)*2;
push1(v,lc,rc,i);
return max(get1(l,r,i,lc,s,mid),get1(l,r,i,rc,mid,e));
}
void dfs(int u)
{
subt[u]=1;
for (int i=0;i+1<nei[u].size();i++)
if (nei[u][i].first==par[u])
swap(nei[u][i],nei[u][i+1]);
if (par[u]) nei[u].pop_back();
for (auto [i,w]:nei[u])
if (i!=par[u])
par[i]=u, dfs(i), subt[u]+=subt[i];
for (int i=(int)nei[u].size()-1;i>0;i--)
if (subt[nei[u][i].first]>subt[nei[u][i-1].first])
swap(nei[u][i], nei[u][i-1]);
}
void doit(int u)
{
if (nei[u].empty()) return;
nx[nei[u][0].first]=nx[u], id[nei[u][0].first]=id[u], ind[nei[u][0].first]=ind[u]+1, cnt[id[u]]++;
for (auto [i,w]:nei[u])
{
if (i!=nei[u][0].first)
nx[i]=i, id[i]=t1++, ind[i]=0, cnt[id[i]]++;
doit(i);
}
}
void et(int u,int val=0)
{
st[u]=t++, rev[st[u]]=u;
modify(st[u],st[u]+1,val);
for (auto [i,w]:nei[u])
et(i,val+w), nei1[u].push_back({en[i],i});
en[u]=t;
}
signed main()
{
ios::sync_with_stdio(0);
cin.tie(NULL), cout.tie(NULL);
int q,W;
cin>>n>>q>>W;
int u[n], v[n], w[n];
for (int i=0;i<n-1;i++)
{
cin>>u[i]>>v[i]>>w[i];
nei[u[i]].push_back({v[i],w[i]});
nei[v[i]].push_back({u[i],w[i]});
}
dfs(1);
et(1);
nx[1]=1, id[1]=t1++, cnt[0]++, ind[1]=0;
doit(1);
for (int i=0;i<t1;i++)
seg1[i]=vector<node>(cnt[i]*2);
for (int i=1;i<=n;i++)
{
int x=get(st[nx[i]],st[nx[i]]+1).x;
mod(ind[i],ind[i]+1,(nei[i].size()?get(en[nei[i][0].first],en[i]).x-2*get(st[i],st[i]+1).x+x:0),id[i],0,0,cnt[id[i]]);
}
for (int i=0;i<n-1;i++)
if (st[v[i]]>st[u[i]]) swap(u[i],v[i]);
int ls=0;
while (q--)
{
int d,e;
cin>>d>>e;
d=(d+ls)%(n-1), e=(e+ls)%W;
modify(st[u[d]],en[u[d]],e-w[d]);
int up=u[d];
if (nx[up]!=up)
mod(ind[up],cnt[id[up]],w[d]-e,id[up],0,0,cnt[id[up]]);
while (par[up])
{
if (up==nx[up])
{
int o=get1(ind[par[up]],ind[par[up]]+1,id[par[up]],0,0,cnt[id[par[up]]]);
mod(ind[par[up]],ind[par[up]]+1,get(en[nei[par[up]][0].first],en[par[up]]).x-2*get(st[par[up]],st[par[up]]+1).x+get(st[nx[par[up]]],st[nx[par[up]]]+1).x-o,id[par[up]],0,0,cnt[id[par[up]]]),up=par[up];
}
else up=nx[up];
}
node nd=get(0,n);
int val=nd.x, mx=0,u=rev[nd.i];
while (par[u])
{
if (nei[par[u]][0].first==u)
mx=max(mx,get1(0,ind[par[u]]+1,id[par[u]],0,0,cnt[id[par[u]]])-get(st[nx[u]],st[nx[u]]+1).x), u=nx[u];
else
{
int x=lower_bound(nei1[par[u]].begin(),nei1[par[u]].end(),make_pair(en[u],0ll))-begin(nei1[par[u]]);
mx=max(mx,merge(get(st[par[u]],st[nei[par[u]][x].first]),get(en[nei[par[u]][x].first],en[par[u]])).x-2*get(st[par[u]],st[par[u]]+1).x);
u=par[u];
}
}
ls=val+mx, w[d]=e;
cout<<ls<<endl;
}
return 0;
}
