/**********************GOD**********************/
#include <iostream>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <cstdlib>
#include <string>
#include <vector>
#include <set>
#include <queue>
#include <stack>
#include <iterator>
#include <map>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll , ll> pll;
#define len length()
#define MP make_pair
#define fs first
#define sc second
#define pb push_back
#define all(x) x.begin() , x.end()
#define kill(x) cout << x , exit(0)
#define lid (id << 1)
#define rid (lid | 1)
#define mid ((r + l) >> 1)
const ll MXN = 2e5 + 4;
const ll LOG = 23;
ll n, q, lim;
ll tim, lst;
set<pll> cnd;
vector<pair<pll, ll>> E;
vector<pll> adj[MXN];
ll st[MXN], sz[MXN];
ll dp[MXN];
ll seg[MXN << 2], lz[MXN << 2];
ll par[MXN][LOG];
ll h[MXN];
ll ans[MXN];
ll GetPar(ll v, ll k)
{
for(ll i = 0; i < LOG; i ++)
if(k >> i & 1)
v = par[v][i];
return v;
}
void DFS(ll v = 1, ll p = 0)
{
st[v] = ++ tim; sz[v] = 1;
par[v][0] = p;
for(ll i = 1; i < LOG; i ++)
par[v][i] = par[par[v][i - 1]][i - 1];
for(auto[u, _] : adj[v]) {
if(u == p)
continue;
h[u] = h[v] + 1;
DFS(u, v);
sz[v] += sz[u];
}
}
void dfs(ll v, ll p = 0)
{
for(auto[u, i] : adj[v]) {
if(u == p)
continue;
dp[u] = dp[v] + E[i].sc;
dfs(u, v);
}
}
void Build(ll id = 1, ll l = 1, ll r = n + 1)
{
if(r - l < 2) {
seg[id] = dp[l];
return;
}
Build(lid, l, mid);
Build(rid, mid, r);
seg[id] = max(seg[lid], seg[rid]);
}
void Shift(ll id, ll l, ll r)
{
lz[lid] += lz[id]; lz[rid] += lz[id];
seg[lid] += lz[id]; seg[rid] += lz[id];
lz[id] = 0;
}
void Update(ll ql, ll qr, ll v, ll id = 1, ll l = 1, ll r = n + 1)
{
if(qr <= l || r <= ql)
return;
if(ql <= l && r <= qr) {
seg[id] += v;
return;
}
Shift(id, l, r);
Update(ql, qr, v, lid, l, mid);
Update(ql, qr, v, rid, mid, r);
seg[id] = max(seg[lid], seg[rid]);
}
ll Get(ll ql, ll qr, ll id = 1, ll l = 1, ll r = n + 1)
{
if(qr <= l || r <= ql)
return 0;
if(ql <= l && r <= qr)
return seg[id];
Shift(id, l, r);
return max(Get(ql, qr, lid, l, mid), Get(ql, qr, rid, mid, r));
}
int main()
{
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> q >> lim;
for(ll i = 1; i < n; i ++) {
ll v, u, w; cin >> v >> u >> w;
E.pb({{v, u}, w});
adj[v].pb({u, i - 1});
adj[u].pb({v, i - 1});
}
DFS();
dfs(1);
Build();
for(ll i = 0; i < adj[1].size(); i ++) {
ll u = adj[1][i].fs;
ll x = Get(st[u], st[u] + sz[u]);
ans[u] = x;
cnd.insert({-ans[u], u});
}
while(q --) {
ll x, y; cin >> x >> y;
x = (x + lst) % (n - 1);
y = (y + lst) % lim;
auto[v, u] = E[x].fs;
if(st[v] < st[u])
swap(v, u);
ll c = GetPar(v, h[v] - 1);
cnd.erase({-ans[c], c});
Update(st[v], st[v] + sz[v], y - E[x].sc);
E[x].sc = y;
ans[c] = Get(st[c], st[c] + sz[c]);
cnd.insert({-ans[c], c});
if(cnd.size() == 1)
lst = -(*cnd.begin()).fs;
else {
auto itr = cnd.begin();
lst = -(*itr).fs;
itr ++;
lst -= (*itr).fs;
}
cout << lst << '\n';
}
return 0;
}
/*!
ahkh
*/
