#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define f first
#define s second
const ll inf = 1e18;
#define vll vector<ll>
ll n, q, w;
vector<tuple<ll, ll, ll>> edges;
vector<ll> tin, tout, par, comp, vin;
ll timer = 0;
vector<vector<ll>> g;
void dfs(ll node, ll pari) {
par[node] = pari;
tin[node] = timer++;
vin[tin[node]] = node;
for (auto it : g[node]) {
if (it == pari)
continue;
dfs(it, node);
}
tout[node] = timer - 1;
}
void dfs2(ll node, ll pari, ll id) {
comp[node] = id;
for (auto it : g[node]) {
if (it == pari)
continue;
dfs2(it, node, node == 0 ? it : id);
}
}
struct cand {
ll val;
ll id;
};
struct node {
cand a, b;
ll lazy;
};
node merge(node A, node B) {
vector<cand> v = {A.a, A.b, B.a, B.b};
sort(v.begin(), v.end(), [](cand x, cand y) { return x.val > y.val; });
node res;
res.a = v[0];
res.b = {-(ll)4e18, -1};
for (auto x : v)
if (x.id != res.a.id) {
res.b = x;
break;
}
res.lazy = 0;
return res;
}
struct Seg {
vector<node> seg;
ll sz = 1;
Seg() {
tin.resize(n), tout.resize(n), par.resize(n), comp.resize(n), vin.resize(n);
timer = 0;
dfs(0, -1);
dfs2(0, -1, -1);
for (; sz < n; sz *= 2)
;
seg.resize(2 * sz);
for (ll i = 0; i < n; i++) {
ll v = vin[i];
seg[sz + i].a = {0, comp[v]};
seg[sz + i].b = {-(ll)4e18, -1};
}
for (ll i = sz - 1; i >= 1; --i)
seg[i] = merge(seg[i * 2], seg[i * 2 + 1]);
}
void push(ll i) {
ll x = seg[i].lazy;
if (x == 0)
return;
seg[i * 2].a.val += x;
seg[i * 2].b.val += x;
seg[i * 2].lazy += x;
seg[i * 2 + 1].a.val += x;
seg[i * 2 + 1].b.val += x;
seg[i * 2 + 1].lazy += x;
seg[i].lazy = 0;
}
void update(ll i, ll l, ll r, ll a, ll b, ll w) {
if (l > b || r < a)
return;
if (l >= a && r <= b) {
seg[i].a.val += w;
seg[i].b.val += w;
seg[i].lazy += w;
return;
}
push(i);
ll mid = (l + r) / 2;
update(i * 2, l, mid, a, b, w);
update(i * 2 + 1, mid + 1, r, a, b, w);
seg[i] = merge(seg[i * 2], seg[i * 2 + 1]);
}
void update(ll node, ll w) {
ll l = tin[node], r = tout[node];
update(1, 0, sz - 1, l, r, w);
}
ll ans() {
return seg[1].a.val + seg[1].b.val;
}
};
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> q >> w;
edges.resize(n - 1);
g.resize(n);
for (ll i = 0; i < n - 1; ++i) {
ll a, b, c;
cin >> a >> b >> c;
a--;
b--;
edges[i] = {a, b, c};
g[a].push_back(b);
g[b].push_back(a);
}
Seg seg;
par[0] = -1;
for (ll i = 0; i < n - 1; ++i) {
auto& [a, b, c] = edges[i];
if (par[b] != a)
swap(a, b);
seg.update(b, c);
}
ll last = 0;
while (q--) {
ll d, e;
cin >> d >> e;
ll d1 = (d + last) % (n - 1);
ll e1 = (e + last) % w;
auto& [a, b, c] = edges[d1];
ll dis = e1 - c;
seg.update(b, dis);
c = e1;
last = seg.ans();
cout << last << "\n";
}
}
