#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
using Edge = pair<ll, pll>;
#define fi first
#define se second
#define debug(x) cout << #x << " = " << x << '\n'
const int maxN = 1e5 + 5;
ll n, q, w;
set<pll> adj[maxN];
vector<Edge> edges;
ll id[maxN], dist[maxN];
multiset<ll> dpq;
namespace Subtask12 {
vector<ll> dist;
void dfs(ll cur, ll par, ll cdist) {
dist[cur] = cdist;
for (auto &[nxt, w] : adj[cur]) {
if (nxt == par) continue;
dfs(nxt, cur, cdist+w);
}
}
ll solve() {
dist.assign(n+1, 0);
dfs(1, 0, 0);
ll e1 = -1, mx = -1;
for (ll i = 1; i <= n; i++) {
if (dist[i] > mx) {
mx = dist[i];
e1 = i;
}
}
dist.assign(n+1, 0);
dfs(e1, 0, 0);
ll ret = 0;
for (ll i = 1; i <= n; i++) {
ret = max(ret, dist[i]);
}
return ret;
}
void caller() {
ll last = 0;
//cout << solve() << '\n';
for (ll d, e, i = 1; i <= q; i++) {
scanf("%lld %lld", &d, &e);
d = (d + last) % (n - 1);
e = (e + last) % w;
//debug(d); debug(e);
auto &[w, p] = edges[d];
adj[p.fi].erase({p.se, w});
adj[p.se].erase({p.fi, w});
edges[d].fi = e;
adj[p.fi].insert({p.se, e});
adj[p.se].insert({p.fi, e});
/*
for (ll i = 1; i <= n; i++) {
cout << i << ": ";
for (auto &[j, k] : adj[i]) {
cout << "{" << j << ", " << k << "} ";
}
cout << '\n';
}
*/
last = solve();
printf("%lld\n", last);
}
}
}
namespace Subtask4 {
ll initDia[maxN], parent[maxN];
ll timer, tin[maxN], tout[maxN], byTin[maxN];
struct Segtree {
ll sz;
vector<ll> seg, lazy;
Segtree(ll sz) : sz(sz) {
seg = lazy = vector<ll>((sz << 2) + 1, 0);
}
void updateNode(ll pos, ll val) {
seg[pos] += val;
lazy[pos] += val;
}
void checkLazy(ll pos) {
if (lazy[pos] != 0) {
ll lc = pos << 1, rc = lc | 1;
updateNode(lc, lazy[pos]);
updateNode(rc, lazy[pos]);
lazy[pos] = 0;
}
}
void update(ll pos, ll l, ll r, ll ul, ll ur, ll val) {
if (l > r || ul > ur || l > ur || ul > r) return;
if (ul <= l && r <= ur) {updateNode(pos, val); return;}
checkLazy(pos);
ll m = (l+r) >> 1, lc = pos << 1, rc = lc | 1;
update(lc, l, m, ul, ur, val);
update(rc, m+1, r, ul, ur, val);
seg[pos] = max(seg[lc], seg[rc]);
}
void update(ll ul, ll ur, ll val) {update(1, 1, sz, ul, ur, val);}
ll query(ll pos, ll l, ll r, ll ul, ll ur) {
if (l > r || ul > ur || l > ur || ul > r) return 0;
if (ul <= l && r <= ur) return seg[pos];
checkLazy(pos);
ll m = (l+r) >> 1, lc = pos << 1, rc = lc | 1;
return max(query(lc, l, m, ul, ur), query(rc, m+1, r, ul, ur));
}
ll query(ll ul, ll ur) {return query(1, 1, sz, ul, ur);}
void print() {
for (ll i = 1; i <= sz; i++) {
cout << query(i, i) << ' ';
}
cout << '\n';
}
} S(1), T(1);
void compute(ll cur) {
ll cdist = S.query(tin[cur], tin[cur]);
vector<ll> children(2, cdist);
for (auto &[nxt, w] : adj[cur]) {
children.push_back(S.query(tin[nxt], tout[nxt]));
}
sort(children.begin(), children.end());
reverse(children.begin(), children.end());
//for (auto i : children) {cout << i << ' ';} cout <<'\n';
//cout << cur << ' ' << -T.query(cur, cur) + children[0] + children[1] - 2ll*cdist << '\n';
T.update(cur, cur, -T.query(cur, cur) + children[0] + children[1] - 2ll*cdist);
}
#define debug(x) cout << #x << " = " << x << '\n'
void dfs(ll cur, ll par, ll cdist, ll pw) {
//debug(cur);
tin[cur] = ++timer;
byTin[timer] = cur;
parent[cur] = par;
dist[cur] = cdist;
S.update(tin[cur], tin[cur], cdist);
adj[cur].erase({par, pw});
for (auto &[nxt, w] : adj[cur]) {
if (nxt == par) continue;
dfs(nxt, cur, cdist+w, w);
}
compute(cur);
tout[cur] = timer;
}
void caller() {
S = T = Segtree(n);
dfs(1, 0, 0, 0);
for (auto &[w, p] : edges) {
if (tin[p.fi] > tin[p.se]) {swap(p.fi, p.se);}
}
//S.print(); T.print();
/*
for (ll i = 1; i <= n; i++) {
cout << i << ": ";
for (auto &[j, k] : adj[i]) {
cout << "{" << j << ", " << k << "} ";
}
cout << '\n';
}
*/
ll last = 0;
for (ll d, e, i = 1; i <= q; i++) {
scanf("%lld %lld", &d, &e);
d = (d + last) % (n - 1);
e = (e + last) % w;
//debug(d); debug(e);
auto &[w, p] = edges[d];
//debug(e-w);
S.update(tin[p.se], tout[p.se], e-w);
adj[p.fi].erase({p.se, w});
edges[d].fi = e;
adj[p.fi].insert({p.se, e});
for (ll cur = p.fi; cur > 0; cur = parent[cur]) {
//debug(cur);
compute(cur);
}
//S.print(); T.print();
last = T.query(1, n);
printf("%lld\n", last);
}
}
}
int main() {
scanf("%lld %lld %lld", &n, &q, &w);
bool Star = 1;
bool BinTree = 1;
for (ll a, b, c, i = 1; i < n; i++) {
scanf("%lld %lld %lld", &a, &b, &c);
adj[a].insert({b, c});
adj[b].insert({a, c});
edges.push_back({c, {a, b}});
if (a != 1 && b != 1) {Star = 0;}
int x = min(a, b), y = max(a, b);
if (y != 2*x && y != (2*x + 1)) {BinTree = 0;}
if (b == 1) swap(a, b);
id[i-1] = b;
dist[b] = c;
dpq.insert(c);
}
if (Star) {
dpq.insert(0);
ll last = 0;
for (ll d, e, i = 1; i <= q; i++) {
scanf("%lld %lld", &d, &e);
d = (d + last) % (n - 1);
e = (e + last) % w;
ll change = id[d];
dpq.erase(dpq.lower_bound(dist[change]));
dist[change] = e;
dpq.insert(e);
auto it = dpq.rbegin();
last = *it;
it++;
last += *it;
printf("%lld\n", last);
}
} else if (BinTree) {
Subtask4::caller();
} else {
Subtask12::caller();
}
}
