#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<ll, greater<ll>> s;
for (int i = 1; i < n; ++i)
s.insert(e[i].w);
int d;
ll ee, last(0); while (q--) {
cin >> d >> ee;
d = (d + last) % (n - 1);
ee = (ee + last) % w;
s.erase(s.lower_bound(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';
}
}
}
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 (q <= 5000) subtask12::solve();
else if (g[1].size() == n - 1) subtask3::solve();
else if (subtask4::check()) subtask4::solve();
}
/** /\_/\
* (= ._.)
* / >0 \>1
**/
