#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pii;
int n,q,in[100005],out[100005],mx;
ll W,d[100005],val[100005];
vector<pii> adj[100005];
pii edge[100005];
vector<int> v;
struct node {
ll ans,suff,pref,lca,depth;
} s[2000000];
ll lz[2000000];
node merge(node a, node b) {
node res;
res.depth=max(a.depth,b.depth); //d[x]
res.lca=min(a.lca,b.lca); //d[y]
res.pref=max({a.pref,b.pref,b.depth-2*a.lca}); //d[x]-2d[y]
res.suff=max({a.suff,b.suff,a.depth-2*b.lca}); //-2d[y]+d[z]
res.ans=max({a.ans,b.ans,a.depth+b.pref,a.suff+b.depth}); //d[x]-2d[y]+d[z]
return res;
}
void push(int l, int r, int idx) {
if (lz[idx]==0) return;
s[idx].depth+=lz[idx];
s[idx].lca+=lz[idx];
s[idx].suff-=lz[idx];
s[idx].pref-=lz[idx];
if (l!=r) {
lz[2*idx]+=lz[idx];
lz[2*idx+1]+=lz[idx];
}
lz[idx]=0;
}
void build(int l, int r, int idx) {
if (l==r) {
s[idx].depth=d[v[l]];
s[idx].lca=d[v[l]];
s[idx].pref=-d[v[l]];
s[idx].suff=-d[v[l]];
s[idx].ans=-2e18-5;
} else {
int mid=(l+r)/2;
build(l,mid,2*idx);
build(mid+1,r,2*idx+1);
s[idx]=merge(s[2*idx],s[2*idx+1]);
}
}
void update(int l, int r, int idx, int x, int y, ll val) {
push(l,r,idx);
if (x>r || y<l) return;
if (x<=l && r<=y) {
lz[idx]+=val;
push(l,r,idx);
} else {
int mid=(l+r)/2;
update(l,mid,2*idx,x,y,val);
update(mid+1,r,2*idx+1,x,y,val);
s[idx]=merge(s[2*idx],s[2*idx+1]);
}
}
void dfs(int x, int par) {
in[x]=v.size();
v.push_back(x);
for (auto s : adj[x]) {
if (s.first==par) continue;
d[s.first]=d[x]+s.second;
dfs(s.first,x);
v.push_back(x);
}
out[x]=v.size()-1;
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin>>n>>q>>W;
for (int i=0; i<n-1; ++i) {
int a,b; ll w;
cin>>a>>b>>w;
adj[a].push_back(pii(b,w));
adj[b].push_back(pii(a,w));
edge[i]=pii(a,b);
val[i]=w;
}
dfs(1,0);
mx=v.size()-1;
build(0,mx,1);
ll bef=0;
while (q--) {
ll x,w; cin>>x>>w;
x=(x+bef)%(n-1);
w=(w+bef)%W;
int a=edge[x].first, b=edge[x].second;
if (d[a]>d[b]) swap(a,b);
update(0,mx,1,in[b],out[b],w-val[x]);
val[x]=w;
bef=max(s[1].ans,s[1].depth);
cout<<bef<<"\n";
}
}
