// #pragma GCC optimize("O3, unroll-loops,Ofast")
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
#define tiii tuple<int,int,int>
int INF = numeric_limits<int>::max() / 4;
struct Value {
int ma = -INF;
int ma2 = -INF;
Value() {}
Value(int a) {
ma = a;
}
Value(int a, int b) {
ma = a;
ma2 = b;
}
void add(int v) {
ma += v;
ma2 += v;
}
};
Value comb(Value a, Value b) {
vector<int> r = { a.ma,a.ma2,b.ma,b.ma2 };
sort(r.rbegin(), r.rend());
return Value(r[0], r[1]);
}
struct SegmentTree {
vector<Value> S;
vector<int> lazy;
int len = 1;
SegmentTree(int n) {
while (len < n) {
len <<= 1;
}
S.resize(2 * len);
lazy.resize(2 * len);
}
void upd(int i, int v) {
i += len;
S[i] = Value(v);
for (i /= 2; i > 0; i /= 2) {
S[i] = comb(S[i * 2], S[i * 2 + 1]);
}
}
void apply1(int i, int v) {
S[i].add(v);
lazy[i] += v;
}
void push(int i) {
apply1(i * 2 + 1, lazy[i]);
apply1(i * 2, lazy[i]);
lazy[i] = 0;
}
Value query(int ql, int qr, int l = 0, int r = -2, int i = 1) {
if (r == -2) r = len;
if (ql <= l && r <= qr) {
return S[i];
}
if (r <= ql || qr <= l) {
return Value();
}
int mid = (l + r) / 2;
push(i);
Value a = query(ql, qr, l, mid, i * 2);
Value b = query(ql, qr, mid, r, i * 2 + 1);
return comb(a, b);
}
void apply(int ql, int qr, int v, int l = 0, int r = -2, int i = 1) {
if (r == -2) r = len;
if (ql <= l && r <= qr) {
apply1(i, v);
return;
}
if (r <= ql || qr <= l) return;
int mid = (l + r) / 2;
push(i);
apply(ql, qr, v, l, mid, i * 2); apply(ql, qr, v, mid, r, i * 2 + 1);
S[i] = comb(S[i * 2], S[i * 2 + 1]);
}
};
vector<int> val, cost, ftree;
vector<int> par, sz, depth;
vector<int> start, stop;
vector<vector<pii>> adj;
int timer = 0;
void DFS(int v, int p, int d = 0, int len = 0, int f = -1) {
start[v] = timer++;
depth[v] = d;
sz[v] = 1;
par[v] = p;
ftree[v] = f;
int h = -1;
int s = -1;
for (auto u : adj[v]) {
if (u.first == p) continue;
val[u.first] = len + u.second;
cost[u.first] = u.second;
int nf = f;
if (f == -1) {
nf = u.first;
}
DFS(u.first, v, d + 1, len + u.second, nf);
sz[v] += sz[u.first];
}
stop[v] = timer;
}
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int n, q, w;
cin >> n >> q >> w;
vector<tiii> edges(n - 1);
adj.resize(n);
val.resize(n);
par = sz = val = depth = cost = start = stop = ftree = vector<int>(n, -1);
for (int i = 0; i < n - 1; i++) {
int a, b, c;
cin >> a >> b >> c;
a--; b--;
edges[i] = { a,b,c };
adj[a].push_back({ b,c });
adj[b].push_back({ a,c });
}
DFS(0, 0);
val[0] = 0;
cost[0] = 0;
SegmentTree seg(n);
for (int i = 0; i < n; i++) {
seg.upd(start[i], val[i]);
}
int last = 0;
SegmentTree seg2(adj[0].size());
map<int, int> indch;
for (int i = 0; i < adj[0].size(); i++) {
auto u = adj[0][i];
Value v = seg.query(start[u.first], stop[u.first]);
seg2.upd(i, v.ma);
indch[u.first] = i;
}
while (q--) {
int d, e;
cin >> d >> e;
int edge = (last + d) % (n - 1);
int weight = (e + last) % w;
int a, b, c;
tie(a, b, c) = edges[edge];
if (depth[a] < depth[b]) swap(a, b);
int diff = weight - c;
seg.apply(start[a], stop[a], diff);
edges[edge] = { a,b,weight };
cost[a] = weight;
auto u = ftree[a];
int ans = seg.query(start[u], stop[u]).ma;
seg2.upd(indch[u], ans);
int ma = 0;
for (int i = 0; i < 1; i++) {
Value res = Value();
res = seg2.query(0, adj[0].size());
int rem = seg.query(start[i], start[i] + 1).ma;
int pv = max((res.ma + res.ma2) - (2 * rem), res.ma - rem);
if (pv > ma) {
ma = max({ ma, pv });
}
}
cout << ma << "\n";
last = ma;
}
}
