#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pi pair<int, int>
#define pii pair<int, pi>
#define fi first
#define se second
#define getchar_unlocked getchar_nolock
int n, q, w;
int fst[100005], lst[100005], eu[200005], S[100005], dist[100005];
pi par[100005];
int cnt = 1, in = 1;
vector<pi>v[100005];
void dfs(int x, pi p, int cur){
fst[x] = lst[x] = in;
S[x] = cnt++;
eu[in++] = x;
par[x] = p;
dist[x] = cur;
for(auto [i, j] : v[x]){
if(i == p.fi)continue;
dfs(i, {x, j}, cur + j);
lst[x] = in;
eu[in++] = x;
}
}
struct node{
int s, e, m;
int x, y, z, xy, yz, xyz, lazy;
node *l, *r;
node(int _s, int _e){
s = _s, e = _e, m = (s + e)>>1;
x = y = z = xy = yz = xyz = lazy = 0;
if(s != e)l = new node(s, m), r= new node(m+1, e);
else xy = yz = xyz = -1e18;
}
void propo(){
if(lazy){
x += lazy;
y += 2 * lazy;
z += lazy;
xy -= lazy;
yz -= lazy;
if(s != e)l->lazy += lazy, r->lazy += lazy;
lazy = 0;
}
}
void upd(int a, int b, int c){
if(s == a && b == e)lazy += c;
else{
if(b <= m)l->upd(a, b, c);
else if(a > m)r->upd(a, b, c);
else l->upd(a, m, c), r->upd(m+1, b ,c);
l->propo(), r->propo();
x = max(l->x, r->x);
y = min(l->y, r->y);
z = max(l->z, r->z);
xy = max({l->xy, r->xy, l->x - r->y});
yz = max({l->yz, r->yz, -l->y + r->z});
xyz = max({l->xyz, r->xyz, l->xy + r->z, l->x + r->yz});
}
}
void dbg(){
cout << s << " " << e << " " << x << " " << y << " " << z << " " << xy << " " << yz << " " << xyz << '\n';
if(s == e)return;
l->dbg();
r->dbg();
}
}*root;
pii A[100005];
void solve(){
cin >> n >> q >> w;
for(int i=1;i<n;i++){
int a, b, c;
cin >> a >> b >> c;
v[a].push_back({b, c});
v[b].push_back({a, c});
A[i] = {a, {b, c}};
}
dfs(1, {-1, -1}, 0);
root = new node(1, in);
for(int i=1;i<in;i++)root->upd(i, i, dist[eu[i]]);
//cout << root->xyz << '\n';
//root->dbg();
//for(int i=1;i<in;i++)cout << eu[i] << ' ' << dist[eu[i]] << '\n';
int lastans = 0;
while(q--){
int x, y;
cin >> x >> y;
x = (x + lastans)%(n - 1);
y = (y + lastans)%w;
int tmp = A[x+1].fi;
if(par[tmp].fi != A[x+1].se.fi)tmp = A[x+1].se.fi;
//cerr << tmp << " " << fst[tmp] << " " << lst[tmp] << " " << par[tmp].fi << " " << par[tmp].se << '\n';
root->upd(fst[tmp], lst[tmp], y - par[tmp].se);
//cerr << "died\n";
par[tmp].se = y;
root->propo();
lastans = root->xyz;
cout << lastans << '\n';
}
}
main(){
ios::sync_with_stdio(0);cin.tie(0);
int t = 1;
//cin >> t;
while(t--){
solve();
}
}
