#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define FOR(i,N) for(ll i = 0; i < N; i++)
#define all(x) (x).begin(), (x).end()
#define F first
#define S second
const ll INF = 1e18;
ll N, Q, W;
vector<vector<pair<ll,ll>>> adj;
vector<ll> id, wt;
vector<ll> in, out;
struct node {
ll mn, mx, le, ri, bsf;
};
vector<node> tree;
vector<ll> lazy;
ll t = 0;
void dfs(ll v, ll p) {
in[v] = t++;
for(auto [u, i]: adj[v]) {
if (u == p) continue;
id[i] = u;
dfs(u, v);
}
out[v] = t++;
}
node merge(node a, node b) {
if (a.mn == INF) return b;
if (b.mn == INF) return a;
node res;
res.mn = min(a.mn, b.mn);
res.mx = max(a.mx, b.mx);
res.le = max({a.le, b.le, a.mx - 2 * b.mn});
res.ri = max({a.ri, b.ri, b.mx - 2 * a.mn});
res.bsf = max({a.bsf, b.bsf, a.le + b.mx, b.ri + a.mx});
return res;
}
void pushdown(ll tl, ll tr, ll i) {
if (lazy[i]) {
tree[i].mn += lazy[i];
tree[i].mx += lazy[i];
tree[i].le -= lazy[i];
tree[i].ri -= lazy[i];
if (tl != tr) {
lazy[i * 2] += lazy[i];
lazy[i * 2 + 1] += lazy[i];
}
lazy[i] = 0;
}
}
void update(ll v, ll l, ll r, ll tl = 0, ll tr = N * 2 - 1, ll i = 1) {
pushdown(tl, tr, i);
if (l > r) return ;
if (tl == l && tr == r) {
lazy[i] += v;
pushdown(tl, tr, i);
return ;
}
ll tm = (tl + tr) / 2;
update(v, l, min(r, tm), tl, tm, i * 2);
update(v, max(l, tm + 1), r, tm + 1, tr, i * 2 + 1);
tree[i] = merge(tree[i * 2], tree[i * 2 + 1]);
}
node query(ll l, ll r, ll tl = 0, ll tr = N * 2 - 1, ll i = 1) {
pushdown(tl, tr, i);
if (l > r) return {INF, -INF, -INF, -INF, -INF};
if (tl == l && tr == r) return tree[i];
ll tm = (tl + tr) / 2;
return merge(query(l, min(r, tm), tl, tm, i * 2), query(max(l, tm + 1), r, tm + 1, tr, i * 2 + 1));
}
signed main() {
cin.tie(0); ios::sync_with_stdio(false);
cin >> N >> Q >> W;
adj.resize(N), id.resize(N-1), wt.resize(N-1), in.resize(N), out.resize(N), lazy.resize(N*8), tree.resize(N*8);
FOR(i, N-1) {
ll a, b;
cin >> a >> b >> wt[i];
a--; b--;
adj[a].push_back({b, i});
adj[b].push_back({a, i});
}
dfs(0,0);
FOR(i, N-1) {
update(wt[i], in[id[i]], out[id[i]]-1);
}
ll last = 0;
FOR(i, Q) {
ll d, e;
cin >> d >> e;
d = (d + last) % (N-1);
e = (e + last) % W;
update(e - wt[d], in[id[d]], out[id[d]]-1);
wt[d] = e;
last = query(0, N*2-1).bsf;
cout << last << endl;
}
}
