#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
constexpr ll INF = 1e18;
constexpr int MAXLOG = 18;
constexpr int MAXN = 1e5 + 5;
int N, Q;
ll W;
vector<pair<int,int>> adj[MAXN];
ll wt[MAXN];
pair<int,int> edge[MAXN];
int in[MAXLOG][MAXN], out[MAXLOG][MAXN], dep[MAXLOG][MAXN], anc[MAXLOG][MAXN], child[MAXLOG][MAXN];
int cnt[MAXLOG];
multiset<ll> cenbest[MAXN];
ll chbest[MAXLOG][MAXN];
priority_queue<pair<ll,int>> best;
int sz[MAXN];
bool del[MAXN];
ll st[MAXLOG][MAXN*4], lazy[MAXLOG][MAXN*4];
inline void pushdown(int t, int tl, int tr, int i) {
if (lazy[t][i]) {
st[t][i] += lazy[t][i];
if (tl != tr) {
lazy[t][i * 2] += lazy[t][i];
lazy[t][i * 2 + 1] += lazy[t][i];
}
lazy[t][i] = 0;
}
}
inline void update(int t, ll v, int l, int r, int tl = 0, int tr = N-1, int i = 1) {
pushdown(t, tl, tr, i);
if (l > r) return ;
if (tl == l && tr == r) {
st[t][i] += v;
if (tl != tr) {
lazy[t][i * 2] += v;
lazy[t][i * 2 + 1] += v;
}
return ;
}
int tm = (tl + tr) / 2;
update(t, v, l, min(r, tm), tl, tm, i * 2);
update(t, v, max(l, tm + 1), r, tm + 1, tr, i * 2 + 1);
st[t][i] = max(st[t][i * 2], st[t][i * 2 + 1]);
}
inline ll query(int t, int l, int r, int tl = 0, int tr = N-1, int i = 1) {
pushdown(t, tl, tr, i);
if (l > r) return 0;
if (tl == l && tr == r) return st[t][i];
int tm = (tl + tr) / 2;
return max(query(t, l, min(r, tm), tl, tm, i * 2), query(t, max(l, tm + 1), r, tm + 1, tr, i * 2 + 1));
}
inline int dfsSZ(int v, int p) {
sz[v] = 1;
for(const auto &u: adj[v]) {
if (del[u.F] || u.F == p) continue;
sz[v] += dfsSZ(u.F, v);
}
return sz[v];
}
inline int dfsCEN(int v, int p, int treeSZ) {
for(const auto &u: adj[v]) {
if (del[u.F] || u.F == p || sz[u.F] * 2 <= treeSZ) continue;
return dfsCEN(u.F, v, treeSZ);
}
return v;
}
inline void dfs(int t, int v, int p, ll d, int cen, int ch) {
dep[t][v] = dep[t][p] + 1;
child[t][v] = ch;
anc[t][v] = cen;
in[t][v] = cnt[t]++;
update(t, d, in[t][v], in[t][v]);
for(const auto &u: adj[v]) {
if (u.F == p || del[u.F]) continue;
dfs(t, u.F, v, d + wt[u.S], cen, ch);
}
out[t][v] = cnt[t];
}
inline ll calcbest(int cen) {
if (cenbest[cen].size() == 1) {
return *cenbest[cen].begin();
}
auto it = cenbest[cen].end();
ll a = *--it;
ll b = *--it;
return a + b;
}
inline void build(int v = 0, int t = 0) {
int treeSZ = dfsSZ(v, v);
if (treeSZ <= 1) return ;
int cen = dfsCEN(v, v, treeSZ);
for(const auto &u: adj[cen]) {
if (del[u.F]) continue;
dfs(t, u.F, cen, wt[u.S], cen, u.F);
ll q = query(t, in[t][u.F], out[t][u.F]-1);
cenbest[cen].insert(q);
chbest[t][u.F] = q;
}
best.emplace(calcbest(cen), cen);
del[cen] = true;
for(const auto &u: adj[cen]) {
if (del[u.F]) continue;
build(u.F, t + 1);
}
}
signed main() {
cin.tie(0); ios::sync_with_stdio(false);
cin >> N >> Q >> W;
FOR(i, MAXLOG) FOR(j, MAXN) anc[i][j] = -1;
FOR(i, N-1) {
int a, b;
cin >> a >> b >> wt[i];
a--; b--;
edge[i] = {a, b};
adj[a].emplace_back(b, i);
adj[b].emplace_back(a, i);
}
build();
ll last = 0;
FOR(i, Q) {
int d;
ll e;
cin >> d >> e;
d = (d + last) % (N-1);
e = (e + last) % W;
ll upd = e - wt[d];
wt[d] = e;
auto [u, v] = edge[d];
FOR(t, MAXLOG) {
if (anc[t][u] == anc[t][v] && anc[t][u] != -1 && anc[t][v] != -1 || (anc[t][v] == u || anc[t][u] == v)) {
if (dep[t][v] < dep[t][u]) swap(u, v);
update(t, upd, in[t][v], out[t][v]-1);
int ch = child[t][v];
int cen = anc[t][v];
cenbest[cen].erase(cenbest[cen].find(chbest[t][ch]));
chbest[t][ch] = query(t, in[t][ch], out[t][ch]-1);
cenbest[cen].insert(chbest[t][ch]);
best.emplace(calcbest(cen), cen);
}
}
while (true) {
if (best.top().F != calcbest(best.top().S)) best.pop();
else break;
}
last = best.top().F;
cout << last << '\n';
}
}
