#include <bits/stdc++.h>
using namespace std;
static const int MAXN = 100000;
int n, qu, hihi;
vector<pair<int,int>> adj[MAXN+5];
int dep[MAXN+5], sub[MAXN+5], anc[MAXN+5];
bool vis[MAXN+5];
inline void ulang(int cur, int par){
sub[cur] = 1;
for(const auto &x : adj[cur]){
int v = x.first;
if(v == par) continue;
if(vis[v]){
sub[v] = 0;
continue;
}
ulang(v, cur);
sub[cur] += sub[v];
}
}
inline int centro(int cur, int par, int sz){
for(const auto &x : adj[cur]){
int v = x.first;
if(v == par || vis[v]) continue;
if(sub[v] >= sz/2) return centro(v, cur, sz);
}
return cur;
}
array<int,3> mp[MAXN+5][20];
int cnt;
long long distv[MAXN+5];
inline void euler(int cur, int par, long long tot, int asal, int lvl){
distv[++cnt] = tot;
mp[cur][lvl] = {cnt, 0, asal};
for(const auto &x : adj[cur]){
int v = x.first;
if(v == par || vis[v]) continue;
euler(v, cur, tot + x.second, asal, lvl);
}
mp[cur][lvl][1] = cnt;
}
struct seg{
int l, r;
long long mx, lz;
seg *lf, *rg;
void build(int L, int R){
l = L; r = R;
lz = 0;
if(l == r){
mx = distv[l];
lf = rg = nullptr;
return;
}
int mid = (l+r)>>1;
lf = new seg();
rg = new seg();
lf->build(l, mid);
rg->build(mid+1, r);
mx = max(lf->mx, rg->mx);
}
inline void apply(long long v){
lz += v;
mx += v;
}
inline void push(){
if(lz && l != r){
lf->apply(lz);
rg->apply(lz);
lz = 0;
}
}
void update(int ql, int qr, long long v){
if(qr < l || r < ql) return;
if(ql <= l && r <= qr){
apply(v);
return;
}
push();
lf->update(ql, qr, v);
rg->update(ql, qr, v);
mx = max(lf->mx, rg->mx);
}
inline long long semua() const{
return mx;
}
};
vector<seg*> isi[MAXN+5];
multiset<long long> cari[MAXN+5];
multiset<long long> ans;
void solve(int cur, int prv){
ulang(cur, -1);
int root = centro(cur, prv, sub[cur]);
vis[root] = true;
dep[root] = dep[prv] + 1;
anc[root] = prv;
int id = -1;
for(const auto &x : adj[root]){
int v = x.first;
if(vis[v]) continue;
cnt = 0;
++id;
euler(v, root, x.second, id, dep[root]);
seg *st = new seg();
st->build(1, cnt);
isi[root].push_back(st);
cari[root].insert(st->semua());
}
for(const auto &x : adj[root]){
int v = x.first;
if(!vis[v]) solve(v, root);
}
}
inline long long mul(int idx){
auto &ms = cari[idx];
if(ms.empty()) return 0;
auto it = ms.end(); --it;
long long res = *it;
if(ms.size() >= 2){
--it;
res += *it;
}
return res;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> qu >> hihi;
vector<array<int,3>> edge(n);
for(int i=1;i<n;i++){
int u,v,w;
cin >> u >> v >> w;
edge[i] = {u,v,w};
adj[u].push_back({v,w});
adj[v].push_back({u,w});
}
solve(1, 0);
for(int i=1;i<=n;i++){
ans.insert(mul(i));
}
long long lastt = 0;
while(qu--){
int d,e;
cin >> d >> e;
d = (d + lastt) % (n-1) + 1;
e = (e + lastt) % hihi;
int u = edge[d][0];
int v = edge[d][1];
int oldw = edge[d][2];
if(dep[u] > dep[v]) swap(u,v);
long long delta = e - oldw;
int cur = u;
while(cur){
auto uu = mp[u][dep[cur]];
auto vv = mp[v][dep[cur]];
if(uu[0] < vv[0]) swap(uu, vv);
ans.erase(ans.find(mul(cur)));
seg *st = isi[cur][uu[2]];
cari[cur].erase(cari[cur].find(st->semua()));
st->update(uu[0], uu[1], delta);
cari[cur].insert(st->semua());
ans.insert(mul(cur));
cur = anc[cur];
}
edge[d][2] = e;
lastt = *ans.rbegin();
cout << lastt << '\n';
}
return 0;
}
