#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int MAXN = 1e5 + 5;
const int LG = 20;
const ll INF = 2e18;
int n, q, sz[MAXN], head[MAXN], pa[MAXN], in[MAXN], out[MAXN], trace[MAXN];
ll limW;
vector<int> adj[MAXN], dfs_order;
struct Edge {
int u, v;
ll w;
Edge() {}
Edge(int u, int v, ll w) :
u(u), v(v), w(w) {}
} edges[MAXN];
struct Segment_Tree {
ll *seg, *lazy;
Segment_Tree(int n) :
seg(new ll[4 * n]),
lazy(new ll[4 * n]) {
memset(seg, 0, sizeof(ll) * 4 * n);
memset(lazy, 0, sizeof(ll) * 4 * n);
}
void push(int root, ll val) {
seg[root] += val;
lazy[root] += val;
}
void update(int root, int tl, int tr, int l, int r, ll val) {
if (tl > r || tr < l)
return;
if (tl >= l && tr <= r) {
push(root, val);
return;
}
int tm = (tl + tr) / 2;
push(2 * root, lazy[root]);
push(2 * root + 1, lazy[root]);
lazy[root] = 0;
update(2 * root, tl, tm, l, r, val);
update(2 * root + 1, tm + 1, tr, l, r, val);
seg[root] = max(seg[2 * root], seg[2 * root + 1]);
}
ll get(int root, int tl, int tr, int l, int r) {
if (tl > r || tr < l || l > r)
return -INF;
if (tl >= l && tr <= r)
return seg[root];
int tm = (tl + tr) / 2;
push(2 * root, lazy[root]);
push(2 * root + 1, lazy[root]);
lazy[root] = 0;
return max(get(2 * root, tl, tm, l, r),
get(2 * root + 1, tm + 1, tr, l, r));
}
int get_maxid(int root, int tl, int tr) {
if (tl == tr)
return trace[tl];
int tm = (tl + tr) / 2;
push(2 * root, lazy[root]);
push(2 * root + 1, lazy[root]);
lazy[root] = 0;
if (seg[2 * root] > seg[2 * root + 1])
return get_maxid(2 * root, tl, tm);
else return get_maxid(2 * root + 1, tm + 1, tr);
}
} Find_u(MAXN), Find_v(MAXN);
void dfs_sz(int p, int u) {
pa[u] = p;
sz[u] = 1;
for (auto& id : adj[u]) {
int v = edges[id].u + edges[id].v - u;
if (v == p) {
id = p;
continue;
}
dfs_order.push_back(id);
dfs_sz(u, v);
sz[u] += sz[v];
id = v;
if (sz[v] > sz[adj[u][0]])
swap(id, adj[u][0]);
}
for (int i = 0; i < adj[u].size(); i++) {
if (adj[u][i] == p) {
adj[u].erase(adj[u].begin() + i);
return;
}
}
}
void dfs_head(int u) {
in[u] = ++in[0];
trace[in[u]] = u;
if (u == 1)
head[u] = u;
for (int i = 0; i < adj[u].size(); i++) {
if (i == 0)
head[adj[u][i]] = head[u];
else head[adj[u][i]] = adj[u][i];
dfs_head(adj[u][i]);
}
out[u] = in[0];
}
void update(int u, ll diff) {
Find_u.update(1, 1, n, in[u], out[u], diff);
Find_v.update(1, 1, n, in[u], out[u], -diff);
while (u != 0) {
u = head[u];
int p = pa[u];
if (p != 0) {
int heavy_in = in[adj[p][0]];
int heavy_out = out[adj[p][0]];
ll max_valv = max(Find_u.get(1, 1, n, in[p], heavy_in - 1),
Find_u.get(1, 1, n, heavy_out + 1, out[p]));
ll p_valv = Find_v.get(1, 1, n, in[p], in[p]);
ll upd_valv = max_valv - 2 * Find_u.get(1, 1, n, in[p], in[p]) - p_valv;
Find_v.update(1, 1, n, in[p], in[p], upd_valv);
}
u = p;
}
}
ll get_v(int u) {
ll ans = 0;
while (u != 0) {
ans = max(ans, Find_v.get(1, 1, n, in[head[u]], in[u] - 1));
u = head[u];
int p = pa[u];
if (p != 0) {
int heavy_in = in[u];
int heavy_out = out[u];
ll max_valv = max(Find_u.get(1, 1, n, in[p], heavy_in - 1),
Find_u.get(1, 1, n, heavy_out + 1, out[p]));
ans = max(ans, max_valv - 2 * Find_u.get(1, 1, n, in[p], in[p]));
}
u = p;
}
return ans;
}
ll find_diameter() {
int u = Find_u.get_maxid(1, 1, n);
return Find_u.get(1, 1, n, in[u], in[u]) + get_v(u);
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> q >> limW;
for (int i = 1; i < n; i++) {
int u, v;
ll w;
cin >> u >> v >> w;
edges[i] = {u, v, w};
adj[u].push_back(i);
adj[v].push_back(i);
}
dfs_sz(0, 1);
dfs_head(1);
for (int i = 1; i < n; i++) {
if (edges[i].u == pa[edges[i].v])
swap(edges[i].u, edges[i].v);
}
for (auto i : dfs_order)
update(edges[i].u, edges[i].w);
ll last = 0;
while (q--) {
ll dj, ej;
cin >> dj >> ej;
dj = (dj + last) % (n - 1) + 1;
ej = (ej + last) % limW;
update(edges[dj].u, ej - edges[dj].w);
edges[dj].w = ej;
last = find_diameter();
cout << last << '\n';
}
}
/*
8 1 10
2 1 2
3 2 2
4 3 8
5 1 3
6 3 6
7 5 4
8 5 10
5 3
*/
