#include <bits/stdc++.h>
using namespace std;
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii ;
typedef pair<ll, ll> pll ;
typedef vector<pii> vii ;
typedef vector<int> veci ;
typedef vector<pll> vll ;
typedef vector<ll> vecll;
// find_by_order order_of_key
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define F first
#define S second
#define pb push_back
#define endl '\n'
#define Mp make_pair
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " = " << x << endl
#define set_dec(x) cout << fixed << setprecision(x);
#define fast_io ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io freopen("in.txt" , "r" , stdin) ; freopen("out.txt" , "w" , stdout);
#define lb lower_bound
#define ub upper_bound
#define for1(n) for(int i=1;i<=n;i++)
#define for0(n) for(int i=0;i<n;i++)
#define forn(n) for(int i=n;i>0;i--)
#define pq priority_queue <pii, vector<pii>, greater<pii>>
const ll mod = 1e9+7 ;// 998244353 ;// 1e9+9;
ll inf=1e18;
const int N=1<<17,L=17,bs=701,NN=1e6;
int n,m,k,q,par[N][L],h[N],st[N],en[N],t,pos[N],poss[N];
vector<pair<int,pair<int,ll>>>g[N];
ll w,hh[N],fen[N],val[N],lz[N*2];
struct Node{
ll ans,h1,h2;
int v1;
int v2;
}seg[N*2];
void updd(int i,ll x){
for(;i<N;i+=i&-i)fen[i]+=x;
}
ll gett(int i){
ll ans=0;
for(;i>0;i-=i&-i)ans+=fen[i];
return ans;
}
int LCA(int v1,int v2){
if(h[v1]<h[v2])swap(v1,v2);
int x=h[v1]-h[v2];
for(int j=0;j<L;j++)if(x>>j&1)v1=par[v1][j];
if(v1==v2)return v1;
for(int j=L-1;j>=0;j--)if(par[v1][j]!=par[v2][j]){
v1=par[v1][j];
v2=par[v2][j];
}
return par[v1][0];
}
Node merg(Node a,Node b){
if(b.h1>a.h1)swap(a,b);
Node c=a;
ll ans2=a.h1+b.h1-2*gett(st[LCA(a.v1,b.v1)]),ans3=a.h1+b.h2-2*gett(st[LCA(a.v1,b.v2)]);
if(ans2>c.ans){
c.v2=b.v1;
c.h2=b.h1;
c.ans=ans2;
}
if(ans3>c.ans){
c.v2=b.v2;
c.h2=b.h2;
c.ans=ans3;
}
return c;
}
void DFS(int v){
for(int j=1;j<L;j++)par[v][j]=par[par[v][j-1]][j-1];
st[v]=++t;poss[t]=v;
for(pair<int,pair<int,ll>>u:g[v])if(u.F!=par[v][0]){
par[u.F][0]=v;
h[u.F]=h[v]+1;
hh[u.F]=hh[v]+u.S.S;
pos[u.S.F]=u.F;
DFS(u.F);
}
en[v]=t;
}
inline void build(int l=1,int r=n+1,int v=1){
if(r-l==1){
seg[v].v1=seg[v].v2=poss[l];
seg[v].h1=seg[v].h2=hh[poss[l]];
return;
}
int mid=(l+r)>>1;
build(l,mid,v<<1);
build(mid,r,v<<1|1);
seg[v]=merg(seg[v<<1],seg[v<<1|1]);
}
inline void upd(int lx,int rx,ll x,int l=1,int r=n+1,int v=1){
if(lx>=r || rx<=l)return;
if(lx<=l && r<=rx){
seg[v].h1+=x;seg[v].h2+=x;
lz[v]+=x;
return;
}
if(lz[v]){
lz[v<<1]+=lz[v];lz[v<<1|1]+=lz[v];
seg[v<<1].h1+=lz[v];seg[v<<1].h2+=lz[v];
seg[v<<1|1].h1+=lz[v];seg[v<<1|1].h2+=lz[v];
lz[v]=0;
}
int mid=(l+r)>>1;
upd(lx,rx,x,l,mid,v<<1);
upd(lx,rx,x,mid,r,v<<1|1);
seg[v]=merg(seg[v<<1],seg[v<<1|1]);
}
int main(){
fast_io
cin>>n>>q>>w;
for0(n-1){
int u,v;ll w;cin>>u>>v>>w;
val[i]=w;
g[u].pb({v,{i,w}});
g[v].pb({u,{i,w}});
}
DFS(1);
for1(n){
updd(i,hh[poss[i]]);
updd(i+1,-hh[poss[i]]);
}
// for1(n)cout<<gett(i)<<" ";cout<<endl;
// for1(n)cout<<hh[poss[i]]<<" ";cout<<endl;
// for1(n)cout<<poss[i]<<" ";cout<<endl;
build();
ll lst=0;
while(q--){
ll i,ww;cin>>i>>ww;
i=(i+lst)%(n-1);
ww=(ww+lst)%w;
// cout<<i<<" "<<ww<<endl;
// cout<<pos[i]<<endl;
updd(st[pos[i]],ww-val[i]);updd(en[pos[i]]+1,val[i]-ww);
upd(st[pos[i]],en[pos[i]]+1,ww-val[i]);
val[i]=ww;
lst=seg[1].ans;
cout<<lst<<endl;
}
}
