typedef long long ll;
ll pie(ll army){return (1ll<<army);}
#include <bits/stdc++.h>
#define fr first
#define sc second
#define pb push_back
#define endl '\n'
#define mid ((left+right)>>1)
const ll inf=2000000000000000005;
const int sonsuz=2000000005;
using namespace std;
ll fpow(ll x,ll y,ll m=0){if(y<0){cout<<"powError";return -1;}if(m)x%=m;ll res=1;while(y>0){if(y&1)res*=x;x*=x;if(m){x%=m;res%=m;}y>>=1;}return res;}
struct Seg{
int n;
vector<ll>mx,lazy,arr;
void build(int node=1,int left=0,int right=-1){
if(right==-1)right=n-1;
if(left==right){
mx[node]=arr[left];
return;
}
build(node+1,left,mid);build(node+((mid-left+1)<<1),mid+1,right);
mx[node]=max(mx[node+1],mx[node+((mid-left+1)<<1)]);
}
void push(int node,int left,int right){
if(lazy[node]==0)return;
mx[node]+=lazy[node];
if(left!=right){
lazy[node+1]+=lazy[node];
lazy[node+((mid-left+1)<<1)]+=lazy[node];
}
lazy[node]=0;
}
void yap(vector<ll>v){
arr=v;
n=arr.size();
mx.resize((n<<1)+2);
lazy.resize((n<<1)+2,0);
build();
}
int l,r;ll x;
void up(int node=1,int left=0,int right=-1){
if(right==-1)right=n-1;
if(left>=l&&right<=r){
lazy[node]+=x;
push(node,left,right);
return;
}
push(node,left,right);
if(left>r||right<l)return;
up(node+1,left,mid);up(node+((mid-left+1)<<1),mid+1,right);
mx[node]=max(mx[node+1],mx[node+((mid-left+1)<<1)]);
}
void update(int lef,int rig,ll val){
l=lef;r=rig;x=val;
up();
}
};
int n,q;
ll w,K[100001];
vector<pair<int,ll>>adj[100001];
map<int,pair<int,int>>in_out[100001];
multiset<ll>vals[100001];
vector<Seg>seg[100001];
int level[100001],par[100001],parnum[100001];
pair<int,int>edge[100001];
multiset<ll>bests;
// temp stuff
int sub[100001];
int tim,root;
// temp stuff
void dfs1(int pos,int prev){
sub[pos]=1;
for(auto[x,y]:adj[pos]){
if(level[x]==0&&x!=prev){
dfs1(x,pos);
sub[pos]+=sub[x];
}
}
}
void dfs2(int pos,int prev,ll l,vector<ll>&v){
v[tim]+=l;
in_out[pos][root].fr=tim++;
for(auto[x,y]:adj[pos]){
if(level[x])continue;
if(x==prev)continue;
dfs2(x,pos,y,v);
}
in_out[pos][root].sc=tim;
v[tim]-=l;
}
void cal(int pos,int prev,int num){
dfs1(pos,0);
int total=sub[pos];
int paren=pos;
while(true){
int nex=0;
for(auto[x,y]:adj[pos]){
if(level[x]!=0||x==paren)continue;
if(sub[x]>(total>>1)){
nex=x;
break;
}
}
if(!nex)break;
paren=pos;
pos=nex;
}
par[pos]=prev;
parnum[pos]=num;
level[pos]=level[par[pos]]+1;
seg[pos].resize(adj[pos].size());
vals[pos].insert(0);
vals[pos].insert(0);
root=pos;
in_out[pos][pos]={-1,-1};
for(int i=0;i<adj[pos].size();i++){
if(level[adj[pos][i].fr])continue;
vector<ll>v(adj[pos][i].fr==paren?total-sub[pos]+1:sub[adj[pos][i].fr]+1,0);
tim=0;
dfs2(adj[pos][i].fr,pos,adj[pos][i].sc,v);
for(int j=1;j<v.size();j++){
v[j]+=v[j-1];
}
seg[pos][i].yap(v);
vals[pos].insert(-seg[pos][i].mx[1]);
}
ll topla=-(*vals[pos].begin())-(*(++vals[pos].begin()));
bests.insert(topla);
for(int i=0;i<adj[pos].size();i++){
if(level[adj[pos][i].fr])continue;
cal(adj[pos][i].fr,pos,i);
}
}
int main(){
ios_base::sync_with_stdio(false);cin.tie(NULL);
cin>>n>>q>>w;
for(int i=0;i<n-1;i++){
int a,b;ll c;
cin>>a>>b>>K[i];
edge[i]={a,b};
adj[a].pb({b,K[i]});
adj[b].pb({a,K[i]});
}
cal(1,0,0);
ll ans=0;
while(q--){
int d;ll e;
cin>>d>>e;
d=(d+ans)%(n-1);
e=(e+ans)%w;
if(level[edge[d].fr]>level[edge[d].sc])swap(edge[d].fr,edge[d].sc);
int pos=edge[d].fr;
int sira;
int pos2=edge[d].sc;
while(pos2!=pos){
sira=parnum[pos2];
pos2=par[pos2];
}
ll diff=e-K[d];
K[d]=e;
while(pos){
ll topla=-(*vals[pos].begin())-(*(++vals[pos].begin()));
bests.erase(bests.find(topla));
vals[pos].erase(vals[pos].find(-seg[pos][sira].mx[1]));
int cur=edge[d].fr;
if(in_out[cur][pos].fr<in_out[edge[d].sc][pos].fr)cur=edge[d].sc;
seg[pos][sira].update(in_out[cur][pos].fr,in_out[cur][pos].sc-1,diff);
vals[pos].insert(-seg[pos][sira].mx[1]);
topla=-(*vals[pos].begin())-(*(++vals[pos].begin()));
bests.insert(topla);
sira=parnum[pos];
pos=par[pos];
}
ans=*(--bests.end());
cout<<ans<<endl;
}
}
