#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#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 fast_io ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io freopen("connect.in" , "r" , stdin) ; freopen("connect.out" , "w" , stdout);
ll mod = 1e9+7 ;
const int N = 1e5+23;
vector<pll> g[N];
int st[N], ft[N], tim, pos[N];
vector<pair<pll, ll> > E;
ll seg[4*N], lpz[4*N];
int n, q;
ll h[N];
ll ans[N];
void dfs(int v, int p=0){
st[v]=tim++;
pos[st[v]]=v;
for (auto pp: g[v]){
ll u=pp.F, w=pp.S;
if(u==p) continue;
h[u]=h[v]+w;
dfs(u, v);
}
ft[v]=tim;
}
void Shift(int l, int r, int ind=0){
if(r-l==1)return ;
if(!lpz[ind]) return;
seg[2*ind+1]+=lpz[ind];
seg[2*ind+2]+=lpz[ind];
lpz[2*ind+1]+=lpz[ind];
lpz[2*ind+2]+=lpz[ind];
lpz[ind]=0;
}
void build(int l=0, int r=n, int ind=0){
if(r-l==1){
seg[ind]=h[pos[l]];
return ;
}
int mid=(r+l)>>1;
build(l, mid, 2*ind+1); build(mid, r, 2*ind+2);
seg[ind]=max(seg[2*ind+1], seg[2*ind+2]);
}
void upd(int lx, int rx, ll v, int l=0, int r=n, int ind=0){
Shift(l, r, ind);
if(lx>=r || rx<=l)return;
if(lx<=l && rx>=r){
seg[ind]+=v;
lpz[ind]+=v;
return;
}
int mid=(r+l)>>1;
upd(lx, rx, v, l, mid, 2*ind+1);
upd(lx, rx, v, mid, r, 2*ind+2);
seg[ind]=max(seg[2*ind+1], seg[2*ind+2]);
}
ll get(int lx, int rx, int l=0, int r=n, int ind=0){
Shift(l, r, ind);
if(lx>=r || rx<=l) return 0;
if(lx<=l && rx>=r) return seg[ind];
int mid=(r+l)>>1;
return max(get(lx, rx, l, mid, 2*ind+1), get(lx, rx, mid, r, 2*ind+2));
}
int main()
{
//fast_io
cin>>n>>q>>mod;
for (int i=0; i<n-1; i++){
ll u, v, w; cin>>v>>u>>w;
g[v].pb({u, w}); g[u].pb({v, w});
E.pb({{v, u}, w});
}
dfs(1); build();
set<pll> stt;
vector<pll> temp;
for (auto pp: g[1]){
ll u=pp.F;
stt.insert({get(st[u], ft[u]), u});
temp.pb({st[u], u});
ans[u]=get(st[u], ft[u]);
}
temp.pb({N, N});
sort(all(temp));
ll la=0;
while(q--){
ll i, w;
cin>>i>>w;
i=(i+la)%(n-1);
w=(w+la)%mod;
ll v=E[i].F.F, u=E[i].F.S;
if(st[v]<st[u])swap(u, v);
upd(st[v], ft[v], w-E[i].S);
E[i].S=w;
pll why={st[v], N};
int t=upper_bound(all(temp), why)-temp.begin()-1;
pii ch=temp[t];
auto x=stt.lower_bound(Mp(ans[ch.S], ch.S));
stt.erase(x);
ans[ch.S]=get(st[ch.S], ft[ch.S]);
stt.insert({ans[ch.S], ch.S});
ll res=0;
x=stt.end();
x--;
res+=x->F;
if(x!=stt.begin()){
x--;
res+=x->F;
}
cout<<res<<endl;
la=res;
}
}
