#include <bits/stdc++.h>
#define ff first
#define ss second
#pragma GCC optimize("O3")
#define endl '\n'
using namespace std;
const long long INF = (long long) 1e18;
const int mod = (int) 1e9+7;
const int MAXN = (int) 1e5+5;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
ll n, q, w;
vector<pll> adj[MAXN];
struct ed{
ll a, b, c;
} egs[MAXN];
int kacc[MAXN]; // i. node kaçıncı centroid
int preC[MAXN]; //i. node centroid olmadan önce hangi node centroiddi
int sz[MAXN]; // subtree size'ı
struct yap{
int center, size;
multiset<ll> mx;
multiset<ll> subans;
vector<ll> t;
vector<ll> lazy;
unordered_map<int, int> tin, tout;
vector<ll> der;
vector<int> bpar;
ll ans;
int cnt;
void build(int v, int l, int r){
if(l == r){
t[v] = der[l];
lazy[v] = 0;
}else{
int m = (l + r) / 2;
build(2*v, l, m);
build(2*v+1, m + 1, r);
t[v] = max(t[2*v], t[2*v + 1]);
lazy[v] = 0;
}
}
void push(int v){
lazy[2*v] += lazy[v];
lazy[2*v+1] += lazy[v];
t[2*v] += lazy[v];
t[2*v+1] += lazy[v];
lazy[v] = 0;
}
void upd(int v, int tl, int tr, int l, int r, ll val){
if(l > r) return;
else if(tl == l && tr == r){
t[v] += val;
lazy[v] += val;
}else{
push(v);
int tm = (tl + tr) / 2;
upd(2*v, tl ,tm, l, min(tm, r), val);
upd(2*v+1, tm + 1, tr, max(tm + 1, l), r, val);
t[v] = max(t[2*v], t[2*v + 1]);
}
}
ll que(int v, int tl, int tr, int l, int r){
if(l > r) return 0;
else if(tl == l && tr == r){
return t[v];
}else{
push(v);
int tm = (tl + tr) / 2;
return max(que(2*v, tl, tm, l, min(tm, r)),
que(2*v+1, tm + 1, tr, max(tm + 1, l), r));
}
}
void dfs1(int v, int par){
int sim = cnt++;
tin[v] = sim;
for(pll u: adj[v]){
int j = u.ff;
if(j == par || kacc[j] < kacc[center]) continue;
der[cnt] = der[sim] + u.ss,
dfs1(j, v);
}
tout[v] = cnt - 1;
}
void dfs2(int v, int par){
for(pll u: adj[v]){
int j = u.ff;
if(j == par || kacc[j] < kacc[center]) continue;
bpar[tin[j]] = bpar[tin[v]];
dfs2(j, v);
}
}
ll gt(){
ll ansi1 = (subans.empty() ? 0 : *subans.rbegin());
if(mx.empty()) return ansi1;
auto ite = mx.rbegin();
ll ansi = 0;
ansi += *ite;
ite++;
if(ite == mx.rend()) return max(ansi1, ansi);
else return max(ansi1, ansi + *ite);
}
void init(int node){
center = node;
size = sz[center] + 1;
t.resize(4*size + 5);
lazy.resize(4*size + 5);
der.resize(size);
bpar.resize(size);
der[1] = 0;
bpar[1] = -1;
cnt = 1;
dfs1(center, -1);
for(pll u: adj[center]){
int j = u.ff;
if(kacc[j] < kacc[center]) continue;
bpar[tin[j]] = j;
dfs2(j, center);
}
//cerr<<center<<" "<<size<<" "<<cnt<<endl;
assert(size == cnt);
build(1, 1, size - 1);
for(pii u: adj[center]){
int j = u.ff;
if(kacc[j] < kacc[center]) continue;
mx.insert(que(1, 1, size - 1, tin[j], tout[j]));
}
ans = gt();
}
ll op(int idx, ll val){
if(mx.empty()) return 0;
int u = egs[idx].a, v = egs[idx].b;
ll dif = val - egs[idx].c;
int uu = tin[u], vv = tin[v];
if(uu > vv){
swap(u, v);
swap(uu, vv);
}
auto ali = mx.lower_bound(que(1, 1, size - 1, tin[bpar[vv]], tout[bpar[vv]]));
assert(ali != mx.end());
mx.erase(ali);
upd(1, 1, size - 1, vv, tout[v], dif);
mx.insert(que(1, 1, size - 1, tin[bpar[vv]], tout[bpar[vv]]));
ans = gt();
return ans;
}
} yapi[MAXN];
void dfs(int v, int par, int kc){
sz[v] = 1;
for(pll u: adj[v]){
int j = u.ff;
if(j == par || (kacc[j] != 0 && kacc[j] <= kc)) continue;
dfs(j, v, kc);
sz[v] += sz[j];
}
}
int find_centro(int v, int kc){
int cur = v;
int last = -1;
dfs(v, -1, kc);
bool tru = 1;
while(tru){
tru = 0;
for(pll u: adj[cur]){
int j = u.ff;
if(j == last || (kacc[j] != 0 && kacc[j] <= kc)) continue;
if(sz[j] > sz[v] / 2){
last = cur;
cur = j;
tru = 1;
break;
}
}
}
return cur;
}
void decomp(int v, int kc, int onc){
int centro = find_centro(v, kc);
kacc[centro] = kc;
preC[centro] = onc;
sz[centro] = sz[v];
for(pll u: adj[centro]){
int j = u.ff;
if(kacc[j] != 0 && kacc[j] < kc) continue;
decomp(j, kc + 1, centro);
}
}
int sira[MAXN];
int main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);cout.tie(nullptr);
#ifdef Local
freopen("C:/Users/Admin/Desktop/Yazilim/C/IO/int.txt","r",stdin);
freopen("C:/Users/Admin/Desktop/Yazilim/C/IO/out.txt","w",stdout);
#endif
cin>>n>>q>>w;
for(int i = 0; i < n - 1; i++){
ll a, b, c;
cin>>a>>b>>c;
adj[a].push_back({b, c});
adj[b].push_back({a, c});
egs[i] = {a, b, c};
}
decomp(1, 1, -1);
// initle
for(int i = 1; i <= n; i++){
sira[i] = i;
}
sort(sira + 1, sira + n + 1, [](int a, int b) {
return kacc[a] > kacc[b];
});
for(int i = 1; i <= n; i++){
yapi[sira[i]].init(sira[i]);
int cur = sira[i];
if(preC[cur] != -1){
yapi[preC[cur]].subans.insert(yapi[cur].ans);
}
}
ll last = 0;
for(int i = 0; i < q; i++){
ll d, e;
cin>>d>>e;
d = (d - (n - 1) + last%(n - 1))%(n - 1);
e = (e - w + last%w)%w;
if(d < 0) d += n - 1;
if(e < 0) e += w;
int u = egs[d].a, v = egs[d].b;
if(kacc[u] > kacc[v])
swap(u, v);
int cur = u;
ll ans = yapi[v].gt();
while(cur != -1){
if(preC[cur] != -1){
auto s = yapi[preC[cur]].subans.lower_bound(yapi[cur].ans);
yapi[preC[cur]].subans.erase(s);
}
ans = max(ans, yapi[cur].op(d, e));
if(preC[cur] != -1){
yapi[preC[cur]].subans.insert(yapi[cur].ans);
}
cur = preC[cur];
}
cout<<ans<<endl;
last = ans;
egs[d].c = e;
//islemi yaptıktan sonra egs'de weighti updatele!!!!!
}
#ifdef Local
cout<<endl<<fixed<<setprecision(2)<<1000.0 * clock() / CLOCKS_PER_SEC<< " milliseconds ";
#endif
}
