#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef vector<int> vi;
typedef vector<char> vc;
typedef pair<int, int> pii;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
#define sep ' '
#define F first
#define S second
#define fastIO ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define pb push_back
#define kill(x) {cout << x << endl;return;}
#define sz(x) int(x.size())
#define SP(x) setprecision(x)
#define mod(x) (1ll*x%M+M)%M
#define pq priority_queue
#define mid (l+r)/2
// #define mid2 (l+r+1)/2
#define pll pair<ll, ll>
#define REP(i, k) for (int i = 0 ; i < k ; i ++)
#define MP make_pair
struct Node {
ll a, b, c, d, e, lazy;
Node () {
a = b = c = d = e = -2e18;
lazy = 0;
}
};
const int M = 998244353;
const int N = 3e5+10;
int n, q; ll W;
vector<pair<int, ll>> adj[N];
ll h[N];
vector<pii> E, SE;
int st[N], fn[N];
vector<int> order;
Node node[N<<2];
vector<ll> Ws;
ll weight[N];
Node merge(Node x, Node y) {
Node res;
res.a = max(x.a, y.a);
res.b = max(x.b, y.b);
res.c = max({x.c, x.a + y.b, y.c});
res.d = max({x.d, x.b + y.a, y.d});
res.e = max({x.e, x.c + y.a, x.a + y.d, y.e});
return res;
}
void dolazy(int id) {
ll C = node[id].lazy;
node[id].lazy = 0;
vector<ll> ids = {2*id, 2*id+1};
for(auto i: ids) {
node[i].lazy += C;
node[i].a += C;
node[i].b -= 2*C;
node[i].c -= C;
node[i].d -= C;
}
}
int ID(int u, int v) {
if (u > v) swap(u, v);
return lower_bound(SE.begin(), SE.end(), MP(u, v)) - SE.begin();
}
void dfs(int v = 0, int p = -1) {
for(auto [neigh, w]: adj[v]) {
if (neigh == p) continue;
h[neigh] = 0ll + h[v] + w;
order.pb(h[v]);
st[ID(v, neigh)] = order.size();
dfs(neigh, v);
fn[ID(v, neigh)] = order.size();
}
order.pb(h[v]);
}
void build(int l = 0, int r = n, int id = 1) {
if (r-l == 1) {
node[id].a = order[l];
node[id].b = -2ll*order[l];
node[id].c = node[id].d = -order[l];
node[id].e = 0;
return;
}
build(l, mid, 2*id), build(mid, r, 2*id+1);
node[id] = merge(node[2*id], node[2*id+1]);
}
void upd(int L, int R, ll C, int l=0, int r=n, int id=1) {
if (R <= l || r <= L)
return;
if (L <= l && r <= R) {
node[id].lazy += C;
node[id].a += C;
node[id].b -= 2*C;
node[id].c -= C;
node[id].d -= C;
return;
}
dolazy(id);
upd(L, R, C, l, mid, 2*id), upd(L, R, C, mid, r, 2*id+1);
node[id] = merge(node[2*id], node[2*id+1]);
}
int get(int ind, int l=0, int r=n, int id=1) {
if (r-l == 1) return node[id].a;
dolazy(id);
if (ind < mid) return get(ind, l, mid, 2*id);
return get(ind, mid, r, 2*id+1);
}
void fulldata(int l=0, int r=n, int id=1) {
cout << id << sep << l << sep << r << sep << node[id].a << sep << node[id].b << sep << node[id].e << endl;
if (r-l > 1) fulldata(l, mid, 2*id), fulldata(mid, r, 2*id+1);
}
void solve() {
cin >> n >> q >> W;
int m = n;
for(int i = 0 ; i < n-1 ; i ++) {
int u, v, w; cin >> u >> v >> w; u--, v--; if (u > v) swap(u, v);
adj[u].pb({v, w}), adj[v].pb({u, w});
Ws.pb(w);
E.pb({u, v});
}
SE = E;
sort(SE.begin(), SE.end());
for(int i = 0 ; i < n-1 ; i ++) {
auto [u, v] = E[i];
weight[ID(u, v)] = Ws[i];
}
dfs();
n = 2*n-1;
build();
ll last = 0;
while(q--) {
ll d, w; cin >> d >> w;
d = (0ll + d + last) % (m-1);
w = (0ll + w + last) % W;
auto [u, v] = E[d];
int id = ID(u, v);
int s = st[id], f = fn[id];
// [s, f)
upd(s, f, 0ll + w - weight[id]);
weight[id] = w;
cout << node[1].e << endl;
last = node[1].e;
}
}
// check MAXN
int32_t main() {
fastIO;
solve();
return 0;
}
