#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("avx2")
using namespace std;
using namespace __gnu_pbds;
#define fi first
#define se second
#define all(m) (m).begin(), (m).end()
#define rall(m) (m).rbegin(), (m).rend()
#define vec vector
#define sz(a) (int) (a).size()
#define mpp make_pair
#define mtt make_tuple
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef pair <ll, ll> pll;
typedef pair <int, int> pii;
typedef tuple <int, int, int> tui;
template <typename T>
using prq = priority_queue <T>;
template <typename T>
using pgq = priority_queue <T, vec <T>, greater <T>>;
template <typename T> bool umin(T &a, T b) { return a > b ? a = b, 1 : 0; }
template <typename T> bool umax(T &a, T b) { return a < b ? a = b, 1 : 0; }
struct segt{
int n;
vec <ll> t, p;
segt() {}
segt(int n): n(n), t(4 * n), p(4 * n) {}
void build(int tl, int tr, int v, vec <ll> &d){
if (tl + 1 == tr) return void(t[v] = d[tl]);
int tm = tl + tr >> 1;
build(tl, tm, v * 2 + 1, d);
build(tm, tr, v * 2 + 2, d);
t[v] = max(t[v * 2 + 1], t[v * 2 + 2]);
}
void build(vec <ll> &d){
if (n) build(0, n, 0, d);
}
void apply(int v, ll x){
t[v] += x, p[v] += x;
}
void push(int v){
if (p[v]){
for (int i: {v * 2 + 1, v * 2 + 2}){
apply(i, p[v]);
}
p[v] = 0;
}
}
void upd(int l, int r, ll x, int tl, int tr, int v){
if (l >= r) return;
if (tl == l && tr == r) return void(apply(v, x));
push(v);
int tm = tl + tr >> 1;
upd(l, min(tm, r), x, tl, tm, v * 2 + 1);
upd(max(l, tm), r, x, tm, tr, v * 2 + 2);
t[v] = max(t[v * 2 + 1], t[v * 2 + 2]);
}
void upd(int l, int r, ll x){
if (n) upd(l, r, x, 0, n, 0);
}
ll get(int l, int r, int tl, int tr, int v){
if (l >= r) return 0LL;
if (tl == l && tr == r) return t[v];
push(v);
int tm = tl + tr >> 1;
return max(get(l, min(tm, r), tl, tm, v * 2 + 1),
get(max(l, tm), r, tm, tr, v * 2 + 2));
}
ll get(int l, int r){
if (!n) return 0LL;
return get(l, r, 0, n, 0);
}
};
const int N = 1e5 + 42;
vec <pii> g[N];
int us[N], ss[N];
void siz(int u, int p){
ss[u] = 1;
for (auto &[v, id]: g[u]) if (v != p && !us[v]){
siz(v, u), ss[u] += ss[v];
}
}
int _cen(int u, int p, int n){
for (auto &[v, id]: g[u]) if (v != p && !us[v]){
if (2 * ss[v] > n){
return _cen(v, u, n);
}
}
return u;
}
int cen(int u){
siz(u, u);
return _cen(u, u, ss[u]);
}
ll w[N];
vec <array <int, 4>> ed[N];
multiset <ll, greater <ll>> val[N], s;
segt t[N];
vec <pii> sub[N];
ll get(int u, int i){
return t[u].get(sub[u][i].fi, sub[u][i].se);
}
ll diam(int u){
ll res = 0;
auto it = val[u].begin();
for (int i = 0; it != val[u].end() && i < 2; ++i, ++it){
res += *it;
}
return res;
}
void upd(int u, int i, int l, int r, ll x){
s.erase(s.find(diam(u)));
val[u].erase(val[u].find(get(u, i)));
t[u].upd(l, r, x);
val[u].insert(get(u, i));
s.insert(diam(u));
}
int fi[N], fo[N];
int tmr = 0;
void dfs(int u, int p, int c, int pt, ll h, vec <ll> &d){
fi[u] = tmr++;
d.push_back(h);
for (auto &[v, id]: g[u]) if (v != p && !us[v]){
dfs(v, u, c, pt, h + w[id], d);
ed[id].push_back({c, pt, fi[v], fo[v]});
}
fo[u] = tmr;
}
void dec(int u){
us[u] = 1;
tmr = 0;
vec <ll> d;
for (auto &[v, id]: g[u]) if (!us[v]){
dfs(v, u, u, sz(sub[u]), w[id], d);
ed[id].push_back({u, sz(sub[u]), fi[v], fo[v]});
sub[u].push_back({fi[v], fo[v]});
}
t[u] = segt(sz(d));
t[u].build(d);
for (int i = 0; i < sz(sub[u]); ++i){
val[u].insert(get(u, i));
}
s.insert(diam(u));
for (auto &[v, id]: g[u]) if (!us[v]){
dec(cen(v));
}
}
inline int solve(){
int n, q; ll W;
cin >> n >> q >> W;
for (int i = 0; i < n - 1; ++i){
int u, v;
cin >> u >> v >> w[i], --u, --v;
g[u].push_back({v, i});
g[v].push_back({u, i});
}
dec(cen(0));
ll ans = 0;
while(q--){
int d; ll e;
cin >> d >> e;
d = (d + ans) % (n - 1), e = (e + ans) % W;
for (auto [c, su, l, r]: ed[d]){
upd(c, su, l, r, e - w[d]);
}
w[d] = e;
cout << (ans = *s.begin()) << "\n";
}
return 0;
}
inline void precalc(){}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int tst = 1; //cin >> tst;
precalc();
while(tst--) solve();
return 0;
}
