#include<iostream>
#include<algorithm>
#include<vector>
#include<set>
#define all(x) x.begin(), x.end()
using namespace std;
typedef long long ll;
typedef pair<int, ll> pil;
#define ff first
#define ss second
const int N = 1e5 + 9;
int n, q;
ll w, c;
vector<int> g[N];
struct Edge {
int u, v;
ll w;
int operator()(int x) { return u ^ v ^ x; }
} e[N];
namespace subtask12 {
vector<ll> a[N];
void dfs(int u, int p) {
a[u].assign(2, 0);
for (int id : g[u]) if (p != id) {
int v = e[id](u);
dfs(v, id);
a[u].push_back(a[v][0] + e[id].w);
}
sort(all(a[u]), greater<ll>());
}
ll gogo() {
dfs(1, 0);
ll ans(0);
for (int i = 1; i <= n; ++i)
ans = max(ans, a[i][0] + a[i][1]);
return ans;
}
void solve() {
int d;
ll ee, last(0); while (q--) {
cin >> d >> ee;
d = (d + last) % (n - 1);
ee = (ee + last) % w;
e[d + 1].w = ee;
last = gogo();
cout << last << '\n';
}
}
}
namespace subtask3 {
void solve() {
multiset<int, greater<int>> s;
for (int i = 1; i < n; ++i)
s.insert(e[i].w);
int d, ee, last(0); while (q--) {
cin >> d >> ee;
d = (d + last) % (n - 1);
ee = (ee + last) % w;
s.erase(s.find(e[d + 1].w));
s.insert(e[d + 1].w = ee);
last = *s.begin() + *next(s.begin());
cout << last << '\n';
}
}
}
namespace subtask4 {
bool check() {
for (int i = 1; i < n; ++i)
if (e[i].v / 2 != e[i].u) return false;
return true;
}
struct Node {
ll path, diam;
} seg[1 << 18];
ll wei[N];
void build(int u) {
if (u > n) return;
if (u * 2 > n) seg[u].path = seg[u].diam = wei[u];
else {
int u1 = u << 1, u2 = u1 | 1;
build(u1);
build(u2);
seg[u].path = max(seg[u1].path, seg[u2].path) + wei[u];
seg[u].diam = max({ seg[u1].diam, seg[u2].diam, seg[u1].path + seg[u2].path });
}
}
void upd(int u) {
if (u * 2 > n) seg[u].path = seg[u].diam = wei[u];
else {
int u1 = u << 1, u2 = u1 | 1;
seg[u].path = max(seg[u1].path, seg[u2].path) + wei[u];
}
for (u >>= 1; u; u >>= 1) {
int u1 = u << 1, u2 = u1 | 1;
seg[u].path = max(seg[u1].path, seg[u2].path) + wei[u];
seg[u].diam = max({ seg[u1].diam, seg[u2].diam, seg[u1].path + seg[u2].path });
}
}
void solve() {
wei[1] = 0;
for (int i = 1; i < n; ++i) wei[e[i].v] = e[i].w;
build(1);
int d;
ll ee, last(0); while (q--) {
cin >> d >> ee;
d = (d + last) % (n - 1);
ee = (ee + last) % w;
wei[e[d + 1].v] = ee;
upd(e[d + 1].v);
last = seg[1].diam;
cout << last << '\n';
}
}
}
namespace subtask5 {
int tme = 0, tin[N], tout[N];
int par[N];
ll wei[N];
void dfs(int u) {
tin[u] = ++tme;
for (int id : g[u]) {
int v = e[id](u);
if (v == par[u]) continue;
par[v] = u;
wei[v] = e[id].w;
dfs(v);
}
tout[u] = tme;
}
struct Node {
ll ma, laz;
Node() : ma(0), laz(0) {}
} seg[1 << 18];
void upd(int u, int l, int r, int a, int b, ll v) {
if (a <= l && r <= b) {
seg[u].ma += v;
seg[u].laz += v;
return;
}
int m = (l + r) >> 1, u1 = u << 1, u2 = u1 | 1;
if (seg[u].laz) {
seg[u1].ma += seg[u].laz;
seg[u1].laz += seg[u].laz;
seg[u2].ma += seg[u].laz;
seg[u2].laz += seg[u].laz;
seg[u].laz = 0;
}
if (a <= m) upd(u1, l, m, a, b, v);
if (m < b) upd(u2, m + 1, r, a, b, v);
seg[u].ma = max(seg[u1].ma, seg[u2].ma);
}
ll qry(int u, int l, int r, int a, int b) {
if (b < l || r < a) return 0;
if (a <= l && r <= b) return seg[u].ma;
int m = (l + r) >> 1, u1 = u << 1, u2 = u1 | 1;
if (seg[u].laz) {
seg[u1].ma += seg[u].laz;
seg[u1].laz += seg[u].laz;
seg[u2].ma += seg[u].laz;
seg[u2].laz += seg[u].laz;
seg[u].laz = 0;
}
return max(qry(u1, l, m, a, b), qry(u2, m + 1, r, a, b));
}
ll sum_t[N];
void solve() {
dfs(1);
for (int i = 2; i <= n; ++i)
upd(1, 1, n, tin[i], tout[i], wei[i]);
multiset<ll, greater<ll>> s;
vector<int> a;
s.insert(0);
for (int id : g[1]) {
int v = e[id](1);
a.push_back(v);
sum_t[v] = qry(1, 1, n, tin[v], tout[v]);
s.insert(sum_t[v]);
}
sort(all(a), [&](int a, int b) { return tin[a] < tin[b]; });
int d, u, v, p;
ll ee, last(0); while (q--) {
cin >> d >> ee;
d = (d + last) % (n - 1);
ee = (ee + last) % w;
u = e[d + 1].u, v = e[d + 1].v;
if (par[u] == v) swap(u, v);
// par[v] == u
upd(1, 1, n, tin[v], tout[v], ee - wei[v]);
wei[v] = ee;
p = *prev(upper_bound(all(a), v, [&](int a, int b) { return tin[a] < tin[b]; }));
s.erase(s.find(sum_t[p]));
sum_t[p] = qry(1, 1, n, tin[p], tout[p]);
s.insert(sum_t[p]);
last = *s.begin() + *next(s.begin());
cout << last << '\n';
}
}
}
int main() {
cin.tie(NULL)->sync_with_stdio(false);
cin >> n >> q >> w;
for (int i = 1, u, v; i < n; ++i) {
cin >> e[i].u >> e[i].v >> e[i].w;
if (e[i].u > e[i].v) swap(e[i].u, e[i].v);
g[e[i].u].push_back(i);
g[e[i].v].push_back(i);
}
if (n <= 5000 && q <= 5000) subtask12::solve();
else if (g[1].size() == n - 1) subtask3::solve();
else if (subtask4::check()) subtask4::solve();
else subtask5::solve();
}
/** /\_/\
* (= ._.)
* / >0 \>1
**/
