#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define ll long long
#define mp(x, y) make_pair(x, y)
#define sz(v) ((int) (v).size())
#define all(v) (v).begin(), (v).end()
#define MASK(i) (1LL << (i))
#define BIT(x, y) (((x) >> (y)) & 1)
#define pb push_back
#define max_rng *max_element
#define min_rng *min_element
#define rep(i, n) for(int i = 1, _n = (n); i <= _n; ++i)
#define forn(i, a, b) for(int i = (a), _b = (b); i <= _b; ++i)
#define ford(i, a, b) for(int i = (a), _b = (b); i >= _b; --i)
template <class X, class Y>
inline bool maximize(X &x, Y y) {
return (x < y ? x = y, true : false);
}
template <class X, class Y>
inline bool minimize(X &x, Y y) {
return (x > y ? x = y, true : false);
}
template <class X>
inline void compress(vector<X> &a) {
sort(all(a));
a.resize(unique(all(a)) - a.begin());
}
int ctz(ll x) { return __builtin_ctzll(x); }
int lg(ll x) { return 63 - __builtin_clzll(x); }
int popcount(ll x) { return __builtin_popcount(x); }
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rand(ll l, ll r) {
return l + abs((ll) rng()) % (r - l + 1);
}
const ll oo = (ll) 1e17;
const int inf = (ll) 1e9 + 7, mod = (ll) 1e9 + 7;
const int N = 1e5 + 5, BASE = 307, LOG = 18;
void add(int &x, int y) { x += y; if (x >= mod) x -= mod; }
void sub(int &x, int y) { x -= y; if (x < 0) x += mod; }
int n, Q; ll W;
struct Edge {
int u, v; ll w;
void input() {
cin >> u >> v >> w;
}
} e[N];
vector<pair<int, int>> g[N];
namespace LCA {
int timer = 0;
ll dist[N];
int d[N], in[N], out[N], tour[N << 1];
void dfs(int u = 1, int p = 0) {
in[u] = ++timer;
tour[timer] = u;
for (pair<int, int> i : g[u]) {
int v = i.first;
if (v == p) continue;
d[v] = d[u] + 1;
dist[v] = dist[u] + e[i.second].w;
dfs(v, u);
tour[++timer] = u;
}
out[u] = timer;
}
int rmq[N << 1][LOG + 5];
int min_rmq(int u, int v) {
return d[u] < d[v] ? u : v;
}
void init_rmq() {
rep(i, timer) rmq[i][0] = tour[i];
rep(j, LOG) {
rep(i, timer - MASK(j) + 1) {
rmq[i][j] = min_rmq(rmq[i][j-1], rmq[i + MASK(j-1)][j-1]);
}
}
return;
}
int lca(int u, int v) {
u = in[u]; v = in[v];
if (u > v) swap(u, v);
int h = lg(v - u + 1);
return min_rmq(rmq[u][h], rmq[v - MASK(h) + 1][h]);
}
} using namespace LCA;
namespace CTDL {
ll bit[N << 1];
void upd(int p, ll d) {
for (; p <= timer; p += p & -p)
bit[p] += d;
return;
}
void upd_range(int l, int r, ll d) {
upd(l, +d);
upd(r + 1, -d);
}
ll get(int p) {
ll ans = 0;
for (; p > 0; p -= p & -p)
ans += bit[p];
return ans;
}
ll getDist(int u, int v) {
return get(in[u]) + get(in[v]) - 2 * get(in[lca(u, v)]);
}
struct node {
ll ans;
int u, v;
node(ll a = 0, int b = 0, int c = 0) {
ans = a;
u = b; v = c;
}
void trans(int _u, int _v) {
if (maximize(ans, getDist(_u, _v))) {
u = _u; v = _v;
}
}
void debug() {
cout << ans << ' ' << u << ' ' << v << '\n';
}
};
node st[(N << 3) + 5];
node combine(node &x, node &y) {
if (!x.u) return y;
if (!y.u) return x;
node res = (x.ans < y.ans ? y : x);
res.trans(x.u, y.u); res.trans(x.u, y.v);
res.trans(x.v, y.u); res.trans(x.v, y.v);
return res;
}
void build(int i, int l, int r) {
if (l == r) {
st[i] = node(0, tour[l], tour[l]);
}
else {
int m = (l + r) >> 1;
build(2 * i, l, m);
build(2 * i + 1, m + 1, r);
st[i] = combine(st[2 * i], st[2 * i + 1]);
}
return;
}
void build() { return build(1, 1, timer); }
void upd(int i, int l, int r, int u, int v) {
if (l > v || r < u) return;
if (l >= u && r <= v) return;
int m = (l + r) >> 1;
upd(2 * i, l, m, u, v);
upd(2 * i + 1, m + 1, r, u, v);
st[i] = combine(st[2 * i], st[2 * i + 1]);
}
void upd(int u, int v) {
return upd(1, 1, timer, u, v);
}
ll solve() { return st[1].ans; }
} using namespace CTDL;
signed main(void) {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
// freopen("input.inp", "r", stdin);
cin >> n >> Q >> W;
rep(i, n - 1) {
e[i].input();
g[e[i].u].pb(mp(e[i].v, i));
g[e[i].v].pb(mp(e[i].u, i));
}
dfs();
init_rmq();
rep(i, n - 1) {
if (d[e[i].u] > d[e[i].v])
swap(e[i].u, e[i].v);
}
rep(i, timer) {
upd_range(i, i, dist[tour[i]]);
}
build();
ll lst = 0;
rep(_, Q) {
int d; ll g;
cin >> d >> g;
g = (g + lst) % W;
d = (d + lst) % (n - 1) + 1;
Edge &cur = e[d];
ll change = g - cur.w;
cur.w = g;
upd_range(in[cur.v], out[cur.v], change);
upd(in[cur.v], out[cur.v]);
cout << (lst = solve()) << '\n';
}
return 0;
}
